NAT和HTTP代理分别工作在 (11) 和 (12) 。A网络层 B．

VRP对于Telnet用户支持以下哪几个级别（）.

A.参观级

B.监控级

C.配置级

D.管理级

呕血伴黄疸见于（）

A.慢性胃炎

B.消化性溃疡

C.胆道疾病

D.胃黏膜脱垂症

E.胃癌

儿童不能遵守公认的行为规范和道德标准，不能正常与人交往和学习。这一类行为我们称为__________。

C

There is not enough oil in the world now. As time goes by, it becomes less and less, so what are we going to do when it runs out? Perhaps we will go back to using horses, carriages and bicycles.

In the Second World War, some people didn’t use gas made from petroleum (石油) in their cars. They made gas from wood and plants instead. The car didn’t go fast, but they ran, so this was better than nothing. However, in the future, we can’t cut down all our trees to make gas; we need our trees for other things, too.

Besides different types of gas, we can also use electricity to run our cars, but first we must make the electricity! Some countries have coal and they make electricity with that, but we might not always have coal, either. Other countries have big, strong rivers, and they can use the power of water to turn turbines (涡轮机) and make electricity more easily and cheaply.

We are also able to get power from the ocean tides. We put turbines into the mouth of the river. Then the tide comes in, the water turns the turbines and then it goes out, it turns them again.

Which of these ways will be used to run our cars in the future?

49. When might people have to go back to using horses and carriages?

A. When they are poor.                          B. When they run out of oil.

C. When they need more exercise.           D. When there aren’t any big trees in the world.

50. What did some people use to make gas in the Second World War?

A. Water                   B. Coal                 C. Wood and plants              D. Tides

51. How many ways are suggested to make electricity in the passage?

A. 2                         B. 5                     C. 4                            D. 3

52. The passage is mainly about ________ . 

A. how to run our cars                              B. what to do when oil runs out   

C. different types of gas                         D. the ways to make electricity

猫属于（）动物。

A.哺乳纲

B.偶蹄目

C.爬行纲

D.食肉目