This unit provides basic information on shop tools. Many types of tools are present in the shops you may work in. You will need to know some of the common power tools and equipment found there. In this chapter, you will learn about different types of shop tools and their uses. You will also learn how to select the right shop tool for the job, use and read various types of shop tools, and provide the proper care of the shop tools to keep them in good working condition.

When you have completed this chapter, you will be able to:

  1. Identify the different types of shop tools.
  2. Recognize the safety precautions that apply to shop tools.
  3. Determine the proper uses of table saws.
  4. Identify the different types of grinders.
  5. Determine the proper use of grinders.
  6. Identify the different types of sharpening stones.
  7. Determine the proper uses of sharpening stones.


Shop Tools

Review Questions


Types and Uses

Shop Radial Arm Saw

The radial arm saw (Figure 1) has a circular saw blade that cuts by rotating the blade toward the operator. It can make a variety of cuts, including crosscuts, rips, and miters. With accessories, this saw can also make dadoes, sand, shape, saber saw, surface, and route. The length of the top arm limits the length or width of the cut.

Figure 1 — Radial arm saw.

The procedures used to operate, maintain, and lubricate any shop radial arm saw are found in the manufacturer’s operator and maintenance manuals, along with the safety precautions to be observed. The primary difference between this saw and other saws of this type (field saws) is the location of the controls.

Tilt-Arbor Table Saw

The tilt-arbor table saw (Figure 2) is named for its ability to tilt the saw blade for cutting bevels by tilting the arbor. The arbor, located beneath the table, is controlled by the tilt handwheel.

Figure 2 — Tilt-arbor table saw.

The tilt-arbor table saw is named for its ability to tilt the saw blade for cutting bevels by tilting the arbor. The arbor, located beneath the table, is controlled by the tilt hand wheel.

Compound Miter Saw

The compound miter saw (Figure 3) is used to provide smooth crosscuts and beveled cuts of wood molding, trim, and other materials. This saw uses a circular blade that is pivoted to the correct angle and then dropped onto the material. It has a large compass scale marked in degrees to show the angle of the cut.

Figure 3 — Compound miter saw.

Tile Saw

The tile saw (Figure 4) is used to cut tile and stone. This saw is also known as a wet saw and uses a diamond-tipped circular blade cooled by a continuous stream of water contained in a reservoir. It can operate either like a radial arm saw or a table saw.

Figure 4 — Tile saw.

Band Saw

Figure 5 — Band saw.

Although the band saw (Figure 5) is designed primarily for making curved cuts, it can also be used for straight cutting. Unlike the circular saw, the band saw is frequently used for freehand cutting. Sanding attachments and sanding loops are available for sanding on irregular or curved surfaces.

The band saw has a band or loop-like blade that comes in various widths and strengths for various cutting purposes. It has two large wheels on which the band turns, just as a belt is turned on pulleys. The lower wheel, located below the working table, is connected to the motor directly or by means of pulleys or gears, and serves as the driver pulley. The upper wheel is the driven pulley.

The saw blade is guided and kept in line by two sets of blade guides, one fixed set below the table and one set above with a vertical sliding adjustment. The alignment of the blade is adjusted by a mechanism on the backside of the upper wheel. Tightening and loosening of the blade is provided by another adjustment just behind the upper wheel. Cutoff gauges and ripping fences are sometimes provided for use with band saws, but you will do most of your work freehand with the table clear. With this type of saw, it is difficult to make accurate cuts when you use gauges or fences. The size of a band saw is designated by the diameter of the wheels. Common sizes are 14-, 16-, 18-, 20-, 30-, 36-, 42, and 48-inch diameter wheel machines. The 14-inch size is the smallest practical band saw. With the exception of capacity, all band saws are much the same with regard to maintenance, operation, and adjustment.

A rule of thumb used by many operators is that the width of the blade should be one-eighth the minimum radius to be cut. If the piece on hand has a 4-inch radius, the operator should select a 1/2- inch blade. This ratio does not mean that the minimum radius that can be cut is eight times the width of the blade; the ratio indicates the practical limit for high-speed band saw work. Blades for band saws are designated by points (tooth points per inch), thickness (gauge), and width. The required length of a blade is calculated by adding the circumference of one wheel to twice the distance between the wheel centers. Length can vary within a limit of twice the tension adjustment range. Band saw teeth are shaped like the teeth in a hand ripsaw blade, which means that their fronts are filed at 90 degrees to the line of the saw. Reconditioning procedures are the same for a hand ripsaw, except that very narrow band saws with very small teeth must usually be set and sharpened by special machines.

Drill Press

The drill press (Figure 6) is an electrically operated power machine originally designed as a metal working tool. Accessories, such as jigs, and special techniques make it a versatile woodworking tool as well.

Figure 6 — Drill press.

The motor is mounted to a bracket at the rear of the head assembly and designed to permit V-belt changing for desired spindle speed without removing the motor from its mounting bracket. Four spindle speeds are obtained by locating the V-belt on any one of four steps of the spindle-driven and motor-driven pulleys. The belt tensioning rod keeps proper tension on the belt so it does not slip.

The controls of all drill presses are similar. The terms right and left are relative to the operator’s position standing in front of and facing the drill press. Forward applies to movement toward the operator. Rearward applies to movement away from the operator

Specific instructions on how to safely use the drill press are in the manufacturers’ documentation. The on/off switch is located in the front of the drill press for easy access.

The spindle and quill feed handles radiate from the spindle and quill pinion feed hub, which is located on the lower right-front side of the head assembly. Pulling forward and down on any one of the three spindles and quill feed handles, which point upward at the time, moves the spindle and quill assembly downward. Release the feed handle and the spindle and quill assembly return to the retracted or upper position by spring action.

The quill lock handle is located at the lower left-front side of the head assembly. Turn the quill lock handle clockwise to lock the quill at a desired operating position. Release the quill by turning the quill lock handle counterclockwise. However, in most cases, the quill lock handle will be in the released position.

The head lock handle is located at the left-rear side of the head assembly. Turn the head lock handle clockwise to lock the head assembly at a desired vertical height on the bench column. Turn the head lock handle counterclockwise to release the head assembly. When operating the drill press, you must ensure that the head lock handle is tight at all times.

The head support collar handle is located at the right side of the head support collar and below the head assembly. The handle locks the head support collar, which secures the head vertically on the bench column, and prevents the head from dropping when the head lock handle is released. Turn the head support collar lock handle clockwise to lock the support to the bench column and counterclockwise to release the support. When operating the drill press, ensure that the head support collar lock handle is tight at all times.

As you face the drill press, the tilting table lock handle is located at the right-rear side of the tilting table bracket. The lock pin secures the table at a horizontal or 45-degree angle. This position allows you to move the table to the side, out of the way for long pieces of wood. The table support collar allows you to raise or lower the table. Turn the tilting table lock handle counterclockwise to release the tilting table bracket so it can be moved up and down or around the bench column. Lock the tilting table assembly at the desired height by turning the lock handle clockwise. When operating the drill press, ensure that the tilting table lock handle is tight at all times.

The adjustable locknut is located on the depth gauge rod. The purpose of the adjustable locknut is to regulate depth drilling. Turn the adjustable locknut clockwise to decrease the downward travel of the spindle. The locknut must be secured against the depth pointer during drill press operation. The depth of the hole is shown on the depth scale.

Woodworking Lathe

The woodworking lathe is, without question, the oldest of all woodworking machines. In its early form, it consisted of two holding centers with the suspended stock rotated by an endless rope belt. It was operated by having one person pull on the rope hand over hand while the cutting was done by a second person holding crude hand tools on an improvised beam rest.

The actual operations of woodturning performed on a modern lathe are still done to a great degree with wood-turner’s hand tools. Machine lathe work is coming more and more into use with the introduction of newly designed lathes for that purpose. The size of a lathe is determined by the maximum diameter of the work it can swing over its bed. The lathe is used in turning or shaping round drums, disks, or any object that requires a true diameter. There are various sizes and types of wood lathes, ranging from very small sizes for delicate work to large surface or bull lathes that can swing jobs 15 feet in diameter.

A type of woodworking lathe that you may find in your shop is illustrated in Figure 7. It is made in three sizes to swing 16-, 20-, and 24-inch diameter stock. The lathe has four major parts: the bed, headstock, tailstock, and tool rest. The lathe shown in Figure 7 has an iron bed and comes in assorted lengths. The bed is a broad, flat surface that supports the other parts of the machine.

Figure 7 — Woodworking lathe.

The headstock is mounted on the left end of the lathe bed. All power for the lathe is transmitted through the headstock. It has a fully enclosed motor that gives variable spindle speed. The spindle is threaded at the front end to receive the faceplate. A faceplate attachment to the motor spindle is furnished to hold or mount small jobs having large diameters. There is also a flange on the rear end of the spindle to receive large faceplates, which are held securely by four stud bolts.

The tailstock is located on the right end of the lathe and is movable along the length of the bed. It supports one end of the work while the other end is being turned by the headstock spur. The tail center can be removed from the stock by simply backing the screw. The shank is tapered to center the point automatically.

Most large lathes are provided with a power-feeding carriage. A cone-pulley belt arrangement provides power from the motor, and trackways are cast to the inside of the bed for sliding the carriage back and forth. All machines have a metal bar that can be attached to the bed of the lathe between the operator and the work. This bar serves as a hand tool rest and provides support for the operator in guiding tools along the work. It may be of any size and is adjustable to any desired position.

In lathe work, wood is rotated against the special cutting tools, illustrated in Figure 8. These tools include turning gouges; skew chisels; parting tools; and round nose, square nose, and spear-point chisels. Other cutting tools are toothing irons and auxiliary aids, such as calipers, dividers, and templates.

Figure 8 — Lathe cutting tools

Turning gouges are used chiefly to rough out nearly all shapes in spindle turning. The gouge sizes vary from 1/8 to 2 inches or more, with 1/4-, 3/4-, and 1-inch sizes being the most common.

Skew chisels are used for smoothing cuts to finish a surface, turning beads, trimming ends or shoulders, and making V-cuts. They are made in sizes from 1/8 to 2 1/2 inches in width and in right-  and left-handed pairs.

Parting tools are used to cut recesses or grooves with straight sides and a flat bottom, and also to cut off finished work from the faceplate. These tools are available in sizes ranging from 1/8 to 3/4 inch.

The toothing iron, shown in Figure 9, is basically a square nose turning chisel with a series of parallel grooves cut into the top surface of the iron. These turning tools are used for rough turning of segment work mounted on the faceplate. The points of the toothing iron created by the parallel grooves serve as a series of spear-point chisels. The toothing iron is made with coarse, medium, and fine parallel grooves and varies from 1 /2 to 2 inches in width.

Figure 9 — Toothing iron.


The jointer (Figure 10) is a machine for power planing stock on faces, edges, and ends. The size of a jointer is designated by the width in inches of the cutter head. Sizes range from 4 to 36 inches.

Figure 10 — 6-inch jointer.

The planing is done by a revolving cutter head equipped with two or more knives, as shown in Figure 11. Tightening the set screws forces the throat piece against the knife for removal.

Figure 11 — Four-blade cutting head for a jointer.

The principle on which the jointer functions is illustrated in Figure 12. The table consists of two parts on either side of the cutter head. The stock is started on the infeed table and fed past the cutter head onto the outfeed table.

Figure 12 — Operating principle of a jointer.

The surface of the outfeed table must be exactly level with the highest point reached by the knife edges. The surface of the infeed table is depressed below the surface of the outfeed table an amount equal to the desired depth of cut. The usual depth of cut is about 1/16 to 1/8 inch.


A single surfacer, also called a single planer, is shown in Figure 13. This machine surfaces stock on one face, the upper face, only. Double surfacers, which surface both faces at the same time, are used only in large planing mills.

Figure 13 — Single surfacer.

The single surfacer cuts with a cutter head similar to the one on the jointer, but the single surfacer’s cutter head is located above, instead of just below, the drive rollers. The part adjacent to the cutter head is pressed down against the feed bed by the chip breakers just ahead of the cutter head and the pressure bar just behind the cutter heads. The pressure bar temporarily straightens out any warp a piece may have; a piece that goes into the surfacer warped will come out warped. This result is not a defect in the machine; the surfacer is designed for surfacing only, not for truing warped stock.

If you desire true plane surfaces, the face of the stock that goes down in the surfacer must be trued on the jointer before feeding the piece through the surfacer. If the face that goes down in the surfacer is true, the surfacer will plane the other face true.



The spindle shaper is one of the most dangerous machines used in the shop.

Use extreme caution at all times.

The shaper is designed primarily for edging curved stock and cutting ornamental edges, as on moldings. It can also be used for rabbeting, grooving, fluting, and beading.

For shaping the side edges on a rectangular piece, a light-duty shaper has an adjustable fence, such as the one shown on the shaper in Figure 14. For shaping the end edges on a rectangular piece, a machine of this type has a sliding fence similar to the cutoff gauge on a circular saw. The sliding fence slides in the groove shown in the table top.

Figure 14 — Light-duty shaper with adjustable fence.

On larger machines, the fence consists of a board straightedge, clamped to the table with a hand screw (Figure 15). A semicircular opening is sawed in the edge of the straightedge to accommodate the spindle and the cutters. Whenever possible, a guard of the type shown in the figure should be placed over the spindle.

Figure 15 — Heavy-duty shaper with fence and guard.

The table usually has a couple of holes, one on either side of the spindle, into which vertical starter pins can be inserted for shaping curved edges. When a curved edge is being shaped, the piece is guided by and steadied against the starter pin and the ball bearing collar on the spindle.

A flat cutter for a shaper is shown in Figure 16. When in use, the cutter is mounted on a vertical spindle and held in place by a hexagonal spindle nut. A grooved collar is placed below and above the cutter to receive the edges of the knives. Ball bearing collars are available for use as guides on irregular work where the fence is not used. The part of the edge that is to remain uncut runs against a ball bearing collar underneath the cutter. Cutters come with cutting edges in a great variety of shapes.

Figure 16 — Three-wing cutter for a shaper.

Bench Grinder

 Bench grinders (Figure 17) are used for reshaping and sharpening chisels, drills, hatchets, and other similar small hand tools.

Figure 17 — Bench grinder.

 The bench grinder consists of a tool rest, an abrasive wheel, and an encased motor assembly. The clamp is used for fastening the grinder to a working surface. The rest supports tools that are being ground. It is adjustable and may be moved from side to side. The abrasive wheel may be changed, depending upon the type of metal being ground.

Valve Grinder

The valve grinder (Figure 18) is a hand-operated special grinder. It is used for grinding the valve seating surfaces on combustion engines. It grinds with cutting blades on a rotating shaft instead of an abrasive wheel. It consists of a handle, interchangeable shafts, and cutting blades. A suction cup valve grinder (Figure 19) is used to grind non-slotted valves to fit seating surfaces.

Figure 18 — Valve grinder.

Figure 19 — Suction cup valve grinder

Sharpening Stones

Sharpening stones usually have one coarse face and one fine face. This design could combine coarse artificial stone with fine natural stone. The coarse edge is used to remove nicks and reshape the tool being sharpened. The fine edge is used to complete the sharpening process and put a keen edge on the tool. Sharpening stones are available in various shapes and sizes, as shown in Figure 20.

Figure 20 — Sharpening stones.

Using a Tilt-Arbor Table Saw

To rip stock, remove the cutoff gauges and set the rip fence away from the saw by a distance equal to the desired width of the piece to be ripped off. Place the piece with one edge against the fence and feed through with the fence as a guide.

To cut stock square, set the cutoff gauge at 90 degrees to the line of the saw, and set the ripping fence to the outside edge of the table, away from the stock to be cut. Place the piece with one edge against the cutoff gauge, hold it firmly, and feed it through by pushing the gauge along its slot. To cut stock at an angle other than 90 degrees, also known as miter cutting, the process is similar, except that the cutoff gauge is set to bring the piece to the desired angle with the line of the saw.

For ordinary ripping or cutting, the saw blade should extend above the table top 1/8 to 1/4 inch plus the thickness of the piece to be sawed. The vertical position of the saw is controlled by the depth of the cut handwheel. The angle of the saw blade is controlled by the tilt handwheel. Except when its removal is absolutely unavoidable, the guard must be kept in place.

The slot in the table through which the saw blade extends is called the throat. The throat is contained in a small, removable section of the table called the throat plate. The throat plate is removed when it is necessary to insert a wrench to remove the saw blade. The blade is held on the arbor by the arbor nut. A saw is usually equipped with several throat plates, containing throats of various widths. A wider throat is required when a dado head is used on the saw. A dado head consists of two outside grooving saws, which are much like combination saws, and as many intermediate chisel-type cutters (chippers) as required to make up the designated width of the groove or dado. Grooving saws are usually 1/8-inch thick, so one grooving saw will cut a 1/8-inch groove, and two used together will cut a 1/4-inch groove. Intermediate cutters come in various thicknesses.

Using a Bench Grinder


Wear eye protection and watch your fingers. Firmly hold tools being shaped firmly so they will not catch in abrasive wheel and cause injury.



Never use a cracked wheel. Before using a wheel, tap it lightly with a mallet. A ringing sound indicates that the wheel is satisfactory; a dull sound indicates that the wheel may be cracked.

The following steps describe how to use a bench grinder properly:

  1. Before using, inspect the grinder and abrasive wheel, checking for cracks or breaks on exposed surfaces.
  2. Loosen the wing nut on the rest, adjust the rest (Figure 21), and tighten the wing nut.
  3. Support the tool to be ground on the rest.

Figure 21 — Adjust the tool rest.

Figure 22 — Sharpen the tool.

  1. Move the tool back and forth across the abrasive wheel face to be sure of an evenly ground surface (Figure 22).
  2. Stop grinding occasionally to check for the desired edge.

When the desired edge is obtained, you are finished. Store grinder in its designated storage area.

Using a Sharpening Stone


 Keep your fingers clear of the hinge area of a pocket knife.



Unless stone is already oil-impregnated, apply a light coat of oil before and during use.

The following steps describe how to use a sharpening stone properly:

  1. Hold the handle of the blade to be sharpened in one hand and extend the blade across the stone.
  2. Press down on the blade with the fingers of the other hand (Figure 23).

Figure 23 — Using a sharpening stone.

  1. With a circular or arch motion, stroke the blade against the sharpening stone.
  2. After several strokes, reverse the blade and stroke the other side in a similar manner. Use light, even pressure.
  3. Repeat stroking action until the desired edge is obtained.

Care of Shop Tools

Observe the following guidelines when working with all shop tools:

Care of Tilt-Arbor Table Saws

Observe the following guidelines when working with a tilt-arbor table saw:

Care of Band Saws

Observe the following guidelines when working with a band saw:

 Care of Drill Presses

Observe the following guidelines when working with a drill press:

Care of Woodworking Lathes

Lathe turning can be extremely dangerous. You must use particular care in this work.

 Observe the following guidelines when working with a woodworking lathe:

Care of Jointers

The jointer is one of the most dangerous machines in the woodworking shop. Only experienced and responsible personnel should be allowed to operate it.

Observe the following guidelines when working with a jointer:

The level of the outfeed table must be checked frequently to ensure the surface is exactly even with the highest point reached by the knife edges. If the outfeed table is too high, the cut will become progressively shallower as the piece is fed through. If the out feed table is too low, the piece will drop downward as it leaves the infeed table, and the cut for the last inch or so will be too deep.

To set the outfeed table to the correct height:

  1. Feed a piece of waste stock past the cutter head until a few inches of it lie on the outfeed table.
  2. Stop the machine and look under the outfeed end of the piece. If the outfeed table is too low, a space will be between the surface of the table and the lower face of the piece. Raise the outfeed table until this space is eliminated. If no space appears, lower the outfeed table until a space does appear.
  3. Run the stock back through the machine. If there is still space, raise the table just enough to eliminate it.

Note that the cutter head cuts toward the infeed table. To cut with the grain, you must place the piece with the grain running toward the infeed table. A piece is edged by feeding it through on edge with one of the faces held against the fence. A piece is surfaced by feeding it through flat with one of the edges against the fence. This operation should be limited to straightening the face of the stock. The fence can be set at 90 degrees to produce squared faces and edges or at any desired angle to produce beveled edges or ends.

Only use sharp and evenly balanced knives in a jointer cutting head. The knives must not be set to take too heavy a cut because a kickback is almost certain to result, especially if there is a knot or change of grain in the stock. You must securely refasten the knives after the machine has been standing in a cold building over the weekend.

Each hand-fed jointer should be equipped with a cylindrical cutting head, the throat of which should not exceed 7/16 inch in depth or 5/8 inch in width. It is strongly recommended that no cylinder be used in which the throat exceeds 3 /8 inch in depth or 1/2 inch in width.

Each hand-fed jointer should have an automatic guard that covers all the sections of the head on the working side of the fence or gauge. The guard should automatically adjust horizontally for edge jointing and vertically for surface work, and it should remain in contact with the material at all times.

Care of Surfacers

Observe the following guidelines when working with a surfacer:

Care of Bench Grinders

Observe the following guidelines when working with a bench grinder:

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Review Questions

1. What saw has an arm that limits the length or width of a cut?

A. Band
B. Compound miter
C. Radial arm
D. Table

2. Which of the following saws is pivoted to the correct angle and dropped onto the material?

A. Band
B. Compound miter
C. Radial arm
D. Table

3. Which of the following saws is designed for making curved cuts?

A. Band
B. Compound miter
C. Radial arm
D. Table

4. What shop tool is considered the oldest of all woodworking machines?

A. Drill press
B. Jointer
C. Planer
D. Woodworking lathe

5. What shop tool is also called a single planer?

A. Bench grinder
B. Shaper
C. Surfacer
D. Tile saw

6. What shop tool is designed primarily for edging curved stock and for cutting ornamental edges?

A. Bench grinder
B. Shaper
C. Surfacer
D. Tile saw

7. What grinder is used to sharpen chisels, drills, and other similar small hand tools?

A. Bench
B. Cylinder
C. Tilt arbor
D. Valve

8. What grinder is used to grind the seating surfaces on combustion engines?

A. Bench
B. Cylinder
C. Tilt arbor
D. Valve

9. What type of sharpening stone removes nicks from the tool being sharpened?

A. Bench grinder
B. Coarse edge
C. Fine edge
D. Leather strop

10.What type of sharpening stone completes the sharpening process?

A. Bench grinder
B. Coarse edge
C. Fine edge
D. Leather strop

11.What tilt-arbor table saw attachment must be in place to rip stock?

A. Material clamp
B. Miter fence
C. Rip fence
D. Rip gauge

12.What tilt-arbor table saw attachment must be in place to cut stock square?

A. Cutoff gauge
B. Miter gauge
C. Rip fence
D. Rip gauge

13.The blade of a tilt-arbor table saw should extend what minimum distance above the thickness of the piece to be sawed?

A. 1/4 millimeter
B. 1/2 centimeter
C. 1/8 inch
D. 1/4 inch

14.When using a tilt-arbor table saw to cut a groove, which of the following types of heads should you use?

A. Dado
B. Mortise-and-tenon
C. Rabbet
D. Tooth-and-sprocket

15.Before using a grinder, what first step should you take?

A. Adjust the tool rest
B. Plug the grinder in
C. Inspect the abrasive wheel for cracks or breaks
D. Practice moving the tool back forth across the wheel

16. To ensure an evenly ground surface, you should move the item across the bench grinder in what direction?

A. Back and forth
B. Box shaped
C. Circular
D. Up and down

17.When using a sharpening stone, you should move the blade across the stone in what kind of pattern?

A. Box shaped
B. Circular
C. Diamond
D. Straight line

18.When using a sharpening stone, what type of pressure should you use?

A. Heavy and even
B. Heavy and intermittent
C. Light and even
D. Light and intermittent

19.Which of the following safety precautions applies to all shop tools?

A. Make sure the material is properly secured
B. Always wear ear and eye protection when operating a power tool
C. Ensure the saw blade is set at the proper height above the table
D. Wipe oil and grease from all outside surfaces before and after each use

20.Before making any adjustments to shop tools, what action should you first perform?

A. Clean the tool
B. Remove excess jewelry
C. Select the proper blade
D. Unplug the tool

21.On a tilt-arbor table saw, what item, if any, should be used to push narrow pieces of wood between the blade and gauge?

A. Broom stick
B. Push stick
C. Rip fence gauge
D. None

22.When using a band saw during cold weather, at what temperature will the blade break from the cold?

A. 45 degrees Fahrenheit
B. 54 degrees Fahrenheit
C. 45 degrees Celsius
D. 54 degrees Celsius

23.When using a drill press, what type of pressure should you use on the feed handle?

A. Fast and sporadic
B. Fast and steady
C. Slow and sporadic
D. Slow and steady

24.When using a jointer, in which direction should you plane?

A. Against the grain
B. Diagonally across the grain
C. Perpendicular to the grain
D. With the grain


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Answers to Exercises

1. C
2. B
3. A
4. D
5. C
6. B
7. A
8. D
9. B
10. C
11. C
12. A
13. A
14. A
15. C
16. A
17. B
18. C
19. B
20. D
21. B
22. A
23. D
24. D