题目内容：

A microscope is a useful instrument for observing small objects. By producing a bigger image, the microscope reveals details that are undetectable to the naked eye(裸眼).

Before using the microscope, please read the instructions below.

CAUTION: Microscopes are both delicate and expensive and must be handled with care.

1. Always carry the microscope with two hands — one supporting the base and the other on the arm.

2. Avoid stretching the wire of the lamp across a walkway.

3. Keep the stage clean and always use a glass slide for specimens(样本).

4. To avoid crushing the glass slide when focusing, begin with the lens close to the specimen and gradually back off to focus.

5. Keep the microscope covered to prevent the dust while it is being stored.

HOW TO USE THE MICROSCOPE:

1. Plug(接通电源) in the lamp.

2. Place a sample of what you wish to observe on a slide.

3. Adjust the mirror so it reflects light from the room up into the objective lens. When the mirror is correctly adjusted, a complete circle of light iwll appear when you look through the eyepiece.

4. Place your slide with the specimen directly over the center of the glass circle on teh stage. If it is a wet slide, be sure the bottom of the slide is dry.

5. With the LOW POWER objective leans placed over the slide, use the coarse focus knob to lower the lens to the lowest point.

6. Look through the eyepiece with one eye while closing the other eye. Slowly raise the lens until teh focus is relatively clear.

7. Use the fine focus knob to fine -tune(微调)the focus.

8. Without changing the focus knobs, switch to the HIGH POWER objective lens. Once you have switched to HIGH POWER, use only the fine focus knob to make the image sharper.

1.Which of the following is the correct way to use a microscope according to the text?

A．Use one hand to carry the microscope

B．Place a sample directly on the clean stage

C．When stored, the microscope should be adjusted.

D．Look through the eyepiece with one eye.

2.If you want to observe a thin piece of hair, which of the following should you do first.?

A．Switch to objective lens.                  B．Adjust the mirror.

C．Look through the eyepiece.               D．Place the hair on a glass slide.

3.According to the text, you could see a complete circle of light _____.

A．after correctly adjusting the mirror

B．while looking at the specimen on a glass slide

C．after slowly raising the objective lens

D．before positioning the mirror correctly