问题 填空题

入射光线与平面镜的夹角是25°,则入射角是     度,反射角是     度。

答案

650,65

题目分析:垂直于镜面的直线叫做法线,入射光线与法线的夹角叫入射角,反射光线与法线的夹角叫反射角.光反射定律:反射光线、入射光线分居法线两侧,反射角等于入射角.根据光的反射定律:反射光线、入射光线分居法线两侧,反射角等于入射角.入射光线与平面镜的夹角是25°,则入射角=90°-25°=65°,反射角等于入射角也等于65°.

点评:解决本题的关键是熟知是光的反射定律的应用,以及利用反射定律对反射角和入射角进行计算.

阅读理解

阅读短文,选择正确答案。

    Everyone is talking about bird flu (禽流感). Yes it is a very dangerous disease that could make people very

sick. It will be a few months before we have good medicine for bird flu.

    But that doesn't mean you can't do anything to prevent it now.

    So far, all the people who have caught bird flu have been those who touched sick chickens or their droppings

(粪便). So it is a good idea for people to stay away from live chickens. "People used to (过去常常) go to the

markets to buy live chickens to eat, but now they have to change that habit," said Peter, an expert (专家) from

World Health Organization. But if you do touch a sick bird, remember to wash your hands carefully with soap

at once. Experts (专家) also say having good habits and a healthy body will help keep you safe from bird flu.

For example, don't buy or eat birds that have not been checked. Don't eat anything that has touched raw meat.

Also don't forget to open your windows often and do the sports. Getting enough sleep is also very useful for

fighting illness .If you feel sick, see a doctor right away (马上). At present (目前), no one in Shanghai has bird

flu. But WHO says children under 12 years old could easily get sick with bird flu.

    Try to stay away from people who have the flu, and always cover your mouth and nose when you cough or

sneeze.

1. Which sentence is NOT true according to the passage? [ ]

A. Bird flu is widely known to people.

B. Bird flu is a very dangerous disease.

C. Bird flu could make people sick.

D. We have good medicine for bird flu now.

2. How do people catch bird flu? [ ]

A. By eating cooked eggs.

B. By eating checked birds.

C. By touching sick chickens or their droppings.

D. By forgetting to open windows.

3. Which habit is NOT safe for fighting the illness? [ ]

A. To go to the market to buy live chicken to eat.

B. To wash your hands carefully with soap if you do touch a sick bird.

C. To do some sports regularly and keep healthy.

D. If you feel sick, see a doctor at once.

4. Who is easy to get bird flu? [ ]

A. Everyone

B. Grownups

C. Experts

D. Children under 12 years old

5. What should you do when you cough or sneeze? [ ]

A. Stay away from other people

B. Always close the windows.

C. Cover your mouth and nose

D. Have enough sleep.

填空题