B

As a result of pollution, Lake Erie, on the borders of the USA and Canada, is now without any living things.

    Pollution in water is not simply a matter of “poisons” killing large numbers of fish overnight, Very often the effects of pollution are not noticed for many months or years because the first organisms（生物体）to be affected are either plants or plankton(浮游生物). But these organisms are the food of fish and birds and other creatures. When this food disappears, the fish and birds die too. In this way a whole food chain can be wiped out, and it’s not until dead fish and water birds are seen at the river’s edge or on the seashore that people realize what is happening.

　　Where do the substances which pollute the water come from? There are two main sources of sewage（下水道污物）and industrial waste. As more detergent（洗涤剂）is used in the home, so more of it is finally put into our rivers, lakes and seas. Detergents harm water birds, dissolving the natural substances which keep their feathers water-proof (防水). Sewage itself, if not properly treated, makes the water dirty and prevents all forms of life in rivers and the sea from receiving the oxygen they need. Industrial waste is even more harmful as there are many highly poisonous things in it, such as copper and lead.

　　So, if we want to stop this pollution, the answer is simple: sewage and industrial waste must be made clear before flowing into the water. It may already be too late to save some rivers and lakes, but others can still be saved if the correct action is taken at once.

70. Pollution of water is noticed________.

　　A. when the first organisms are affected　     

B. when a good many fish and birds die

　　C. when poisonous things are poured into water　

D. as soon as the balance of nature is destroyed

71.The living things die because there is no ________in the lake or river.

　　A. water　　　　　            B. fish            　 C. poison　　　　　   D. oxygen

72. Which of the following is harmful according to the passage?

　　A. Organisms               　B. Plants and plankton in the water

　　C. Waste water from cleaning    D. Industrial waste made clear before flowing into the water

73. The way to stop water pollution is to________.

　　A. realize the serious situation clearly

　　B. put oxygen into the river

　　C. make the waste material harmless before flowing into the water

　　D. make special room in the sea for our rubbish

If you do not use  your arms or your legs for some time, they will become weak; when you start using them again, they will slowly become stronger again．Everybody knows that ．yet many people do not seem to know that memory works in the same way．When someone says that he has a good memory, he really means that he keeps his memory in practice by using it．
When someone else says that his memory is poor, he really means that he does not give it enough chance to become strong．If a friend says that his arms and legs are weak, we know that it is his own fault．But if he tells us that he has a poor memory, many of us think that his parents are to blame, and few of us know that it is just his own fault．Have you ever noticed that some people can’t read or write but usually they have better memories? This is because they cannot read or write so they have to remember things; they cannot write them down in a little notebook．They have to remember days, names, songs and stories; so their memories are being exercised the whole time．So if you want to have a good memory, learn from these people:Practise remembering．
【小题1】One has a poor memory mainly because       ．

D
Antarctica is the southernmost place on Earth, and it is larger than the United Sates and 95% of it is covered with ice. The ice is 5 kilometers thick at places and it never melts. At least that is what we thought, but let us keep it that way for now.
The ice seems to be alive as it works its way towards the seA． It forms an ice shelf over the water. The edge breaks away from the shelf and falls into the seA． From here it drifts. Now big pieces of ice become icebergs that can be 160 km long. They now drift north until they finally melt and become part of the ocean. This process is part of a bigger process which in turn forms a cooling system for Earth. This is so important that no country is allowed to control this areA． The treaty (agreement) signed by 12 countries at first and later joined by more, was to prevent any country harming the planet with irresponsible behavior.
The treaty basically states that:
Antarctica can be used for peaceful purposes only.
No country may build a military base there.
No country may do a nuclear test there.
No country may dump nuclear waste there.
Scientists working there will share their information.
Some other rules are there to protect the penguins and seals.
No dogs may run loose.
No planes may land near large groups of animals.
No guns, explosives, or tractors may be used near the animals.
Most important is that every member can inspect any of the other bases if he suspects that the treaty rules are being broken.
While the treaty is not foolproof（万无一失的）, it does play a very important part in the protection of AntarcticA． The more people realize the effects that pollution has on this continent, the bigger the pressure will be on Governments to change the way they look at pollution.
69．Why was it important to sign a treaty for Antarctica?
A．Because the ice on Antarctica will finally melt into the ocean.
B．Because Antarctica is covered with 5 kilometers thick ice.
C．Because Antarctica balances the temperature of Earth.
D．Because there are many big icebergs in AntarcticA．
70．What is the process of the movement of ice in Antarctica?
A．Ice shelf---sea water---iceberg---ice.
B．Sea water---ice---iceberg---ice shelf.
C．Iceberg---ice shelf---ice---sea water.
D．Ice---ice shelf---iceberg---sea water.
71．What is included in the Antarctica treaty?
A．There is no secret research information in AntarcticA．
B．Dogs are not allowed to be raised in AntarcticA．
C．Waste can’t be thrown away in AntarcticA．
D．People can’t bring their guns to AntarcticA．

If you do not use your arm or your legs for some time, they become weak; when you start using them again, they slowly become strong again. Everybody knows that. Yet many people do not seem to know that memory works in the same way. When someone says that he has a good memory, he really means that he keeps his memory in practice by using it. When someone else says that his memory（记忆力） is poor, he really means that he does not give it enough chance to become strong. If a friend says that his arms and legs are weak, we know that it is his own fault(过错). But if he tells us that he has a poor memory, many of us think that his parents are to blame(受责备), and few of us know that it is just his own fault. Have you ever found that some people can’t read or write but usually they have better memories? This is because they cannot read or write and they have to remember things they cannot write down in a little notebook. They have to remember days, names, songs and stories; so their memory is the whole time being exercised. So if you want to have a good memory, learn from the people: Practice remembering.
【小题1】The main reason for one’s poor memory is that _______.

If you are in a town in a western country, you'll often see people walking with their dogs. It is still true that a dog is the most useful animal in the world. But the reason why one keeps a dog has changed Once upon a time, a man met a dog and wanted it to help him in the fight against other animals, and he found that the dog listened to him and did what he told him to. Later people used dogs for  hunting other animals, and the dogs didn't eat what they got until their master agreed. So dogs were used for driving sheep and guarding chicks. But now the people in the towns and cities do not need dogs to fight other animals. Of course they keep them to frighten thieves, but the most important reason is that people feel lonely in the city. For a child, a dog is his best friend when he has no friends to play with. For a young wife, a dog is her child when she doesn’t have her own. For old people, a dog is also a child when their real children have grown up and left. Now people do not have to use a dog, but they keep it as a friend, just like a member of the family.

1._______are more useful than a dog in the world.

A．No other animals                        B．Some animals

C．Many animals                          D．A few animals

2.In the past, people kept dogs because dogs _________.

A．could fight against other animals            B．met the people

C．did not eat other animals                  D．helped and listened to people

3.Now people keep dogs in the cities because dogs_____.

A．fight other animals                      B．are lonely

C．are like their friends                     D．are afraid of the thieves

4.A dog can be _____.

A．a child's friend only                      B．a young woman's son

C．old people's real child                    D．everybody's friend