When a big ship is in very rough(不平坦的) sea, it has to be able to bend(弯) a little, otherwise it may break in two. If one end of the ship is on the top of one huge wave, and the other end is on the top of another, with the middle of the ship hanging in between; or if one huge wave comes up under the middle of the ship, leaving the two ends hanging, the ship's own weight will break its back if it is quite stiff(硬的).

　　To make a big ship elastic(有弹性的) enough to avoid (避开) this danger, it has joints where the sections of the ship come together above the water-line, and these joints (连接处) open and shut slightly as the waves lift one section(部分) of the ship or another. This is enough to save the ship from breaking into pieces.

　　One day a sailor was walking along a passage-way in a big ship during a storm when he was surprised to see a boy sitting comfortably in a chair at the end of the passage-way, which was opposite one of the ship's joints. The boy had a bag of nuts beside him, and every time the ship was lifted by a wave and the joint opened, he put a nut in it. As the ship came down again, the joint closed and cracked(压碎) the nut, gently but firmly. The boy then took it out and put the next one in as the joint opened again.

1．What does a big ship have to do when it is in very rough sea?

2．If one end of the ship is on the top of one huge wave, and the other end is on the top of another, with the middle of the ship hanging in between, what will happen to the ship if it is quite stiff?

3．Why does a big ship have joints?

4．What do these joints do?

5．Where was a sailor walking during the storm in this story?

6．What was he surprised to see?

7．What did the boy have beside him?

8．What did he do?

9．How was the nut cracked?

10．What did the boy do then?

选择填空:

If it ______ tomorrow, we ______ for a picnic.   

[　　]

A. won't rain ... go　　 B. won't rain ... will go

C. doesn't rain ... go   D. doesn't rain ... will go

　　The world is not only hungry, but it is also thirsty for water. This may seem strange to you, since nearly 70 percent（百分比）of the earth's surface is covered with water. But about 97 percent of this huge amount is sea water, or salt water. Man can only drink and use the other 3 percent--the fresh water from rivers, lakes, underground, and other sources（资源）. And we cannot even use all of that, because some of it is in the form of icebergs and glaciers（冰川）. Even worse, some of it has been polluted.

　　However, as things stand today, this small amount of fresh water is still enough for us. But our need for water is increasing（增加）rapidly--almost day by day. Only if we take steps to deal with this problem now can we avoid（避免）a severe（严重）worldwide water shortage later on.

　　Today in most large cities, water is used only once and then sent out into a sewer system（下水道）. From there it returns to the sea or runs into underground storage tanks. But it is possible to pipe used water to a purifying（净化）plant. There it can be treated with chemicals so that it can be used again, just as if it were fresh from a spring.

　　But even if every large city purified and reused its water, we still would not have enough. All we'd have to do to make use of the vast reserves（贮备）of sea water in the world is to remove the salt.

A．As things remain unchanging, this small amount of fresh water is still enough for us.

B．Our need for water is becoming larger and larger.

C．There will be no water shortage in the future.

D．We should take steps to deal with the water shortage problem.

A．treat it with chemicals

B．use it only once

C．send it out into a sewer system

D．make it flow into underground tanks

A．to make enough water

B．to pay more attention to the water shortage problem

C．to pipe used water to a purifying plant

D．to reuse the water