题干

如图所示,鱼缸底部射灯A发出一束光,射向鱼缸壁的B点的并发生反射,其反射光经水面后发生折射,画出反射光线,及其折射光线的大致方向.

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解:过入射点做出法线,从而确定了反射光线位于法线的上侧,并确定了反射角的大小.然后根据反射角等于入射角做出对应的反射光线.

光从水中斜射入空气,所以折射角大于入射角,由此可以做出对应的折射光线.如下图所示:

同类题5

任务型阅读

Question: I have been learning English for about 7 years. ____ And I still can't make myself understood in English. However, I love learning English. How can I learn English well? Please help me.

Answer: Many people have asked me this question. ____ Here I will give you several tips for learning English.

____

    First of all, you must want to learn. If you are not interested in learning English, no class will help you and no book will help you. So you have to be honest with yourself. Ask yourself, “Do I really want to learn English?” If you can't answer “yes” to this question, it is better for you to set English aside until you're ready and willing to learn.

● Set goals (目标).

    To learn English well, you must set some goals. ____ It will also help you to see your progress. Ask yourself, “What are my goals? What areas would I like to improve?” Think about what your goals are, and review once in a while to see that you are making progress toward your goals.

● Practice, practice, and practice.

    After you have set your goals, you have a better idea of what you need to practice. Just like the athlete whose goal is the Olympics must train daily, you as a language learner must practice language every day to make progress toward your goal. ____

A. Want to learn.

B. I think it is not easy to learn it well.

C. Make friends with some Americans online.

D. Reading is a very good way to learn new words.

E. The answers are as different as the people asking the question.

F. The more you practice, the more progress you will make.

G. Having goals will help you remember what areas you want to work on.