问题 选择题

人看到水池里的月亮和鱼的像,它们的形成分别是哪一种现象(  )

A.都是折射现象

B.前者是折射现象,后者是反射现象

C.都是反射现象

D.前者是反射现象,后者是折射现象

答案

答案:D

题目分析:平面镜成像是根据光的反射形成的虚像;当光线从一种介质斜射入另一种介质时,会发生光的折射现象.

解答:解:水池里的“月亮”是平静的水面相当于平面镜,光射到水面时发生反射而成的虚像;

当水中的鱼反射的光线从水中斜射入空气中时,发生光的折射,折射光线进入人眼,眼睛看到了“鱼”并不是实际的鱼,而是鱼的虚像.

故选D.

点评::该题考查了光的反射和光的折射在生活中的现象.

点评:

单项选择题
阅读理解

阅读理解。

     China's giant panda shows the achievement of the international effort to save animals that are now in danger. In television programmes we often see pandas playing funny games. Children have panda toys and beautiful

cards with pictures of lovely pandas in them. They often visit the giant pandas in the zoo on their holiday and

have a good time there.

     However, scientists are worried about the future of giant pandas. They know only about 1,000 giant pandas

remain alive today. They think the giant panda will die out in 30 years if the present conditions are not improved.

      It is reported that the giant pandas have a very low birthrate. About 115 pandas live in zoos and research

centers mainly in China, but during the past ten years they produced only 34 young pandas that are still alive.

Survival rate for giant pandas in the wild are probably the same or lower. There are several reasons for the low

birthrate. The main reason is that male pandas can make love with females in a very short season, only a few

days a year. When they do have babies, females often produce two pandas, but the mother is usually not able to care for both of them. The new-born pandas weigh only a few grams each. They are too weak to live without

special care. In the zoo, scientists can help the mothers care for the young pandas, but those living in the wild

do not get enough help. It is very difficult for mother pandas to bring up their young pandas.

     Conditions for the giant pandas have been worse in recent years. Pandas in China continue to reduce in

number. We know pandas live on bamboos. But sometimes all the bamboos in one area die. The pandas there

have nothing to eat and die of hunger.

     Giant pandas now live in thirteen separate protected areas in China. Several years ago the Chinese

government and the International Wild Life Organization agreed on a project of protecting giant pandas in the

wild. We hope it could be helpful.

1. What does the writer think of the giant pandas?

A. They are funny.

B. They are dirty.

C. They are lovely.

D. They are naughty.

2. According to this passage we know most of the giant pandas live _____.

A. in the wild all over the world

B. in the zoos and research centers

C. in the area where there are plenty of bamboos for them to eat

D. in thirteen separate protected areas in our country

3. Scientists are worried about the future of the giant pandas because _____.

A. sometimes all of the bamboos die in the area where the giant pandas live and they have nothing to eat

B. giant pandas that still live in the wild can not get enough help from humans

C. only a small number of giant pandas remain alive today and their birth rate is too low

D. male and female giant pandas often refuse to make love in the right season

4. The low survival rate of young giant pandas has much to do with the fact that ______.

A. mother pandas are usually unable to take care of both young pandas born

B. female pandas are able to have baby pandas only in a special time

B. young pandas weigh only a few grams each and they are too weak

D. male and female pandas often refuse to have babies in the right time

5. If the present conditions are not improved, giant pandas in the world will disappear _____.

A. in less than a few years

B. in thirteen years

C. in thirty years

D. in the twenties