题目内容
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
70---73 BDCC
解析
天天向上一本好卷系列答案
小学生10分钟应用题系列答案Our boat floated on between walls of forest. It was too thick to allow us a view of the land we were passing through, though we knew from the map that our river must from time to time be passing through chains of hills which crossed the jungle plains. Nowhere did we find a place where we could have landed: where the jungle did not actually spread right down into the river, banks of soft mud prevented us form going ashore. In any case, what would we have gained by landing? The country was full of snakes and other dangerous creatures an
d the jungle was so thick that one would be able to advance slowly, cutting one’s way with knives the whole way. So we stayed in the boat, hoping that when we reached the sea, a friendly fisherman would pick us up and take us to civilization.
As for water, there was a choice. We could drink the muddy river water, o
r die of thirst. We drank the water. Men who have just escaped from what appeared to be certain death lost all worries about such small things as diseases caused by dirty water. In fact, none of us suffered from any illness as a result.
One day we passed another village, but fortunately nobody saw us. We did not wish to risk being taken prisoners a second time: we might not be so lucky as to escape in a stolen boat again.
【小题1】 It can be inferred from the passage that the only thing they could see in a boat was _______.
| A．walls | B．chains of hills | C．tall trees | D．vast land |
A．the country wa s a civilized society | B．the country was a tropical jungle country |
| C．they found a place where they could land | D．they were on a journey home |
| A．They were arrested. | B．They manage d to escape to safety. | C．They were saved by some villagers | D．The passage doesn’t mention it. |
| A．The Problem of Landing | B．An Adventure |
| C．An Entirely New Experience | D．Escape |
It’s a sure sign that summer is over and winter is on the way — leaves that were once deep green turn red, yellow and bright orange. It happens every autumn. But did you ever wonder why?
The leaves start changing color when the nights start getting longer and the temperature starts getting cooler. Some scientists think that as the number of daylight hours shrinks, the leaves stop making chlorophyll which makes plants green. The reason is that the process of making chlorophyll requires sunlight. But according to horticulture (园艺) educator Susan Rose from Colorado State University, it turns out leaves don’t really change color at all. “The fall colors are actually there all along,” she said. “But they are covered by the green chlorophyll. As the chlorophyll stops being produced, the other colors can shine through.”
The kind of color that the leaves are going to change to is determined by the plant’s genetic (基因的) background. In some places, the leaves start changing color in September — before autumn even officially begins. In other places, they don’t change until late October or even November. Some scientists say the leaves have been changing color later than usual in recent years. And they think global warming has something to do with that.
In one study, researchers found that the growing season in the Northern Hemisphere was nearly a week longer, on average, in 2008 than it was in 1982. And a professor from Harvard University found that the leaves, west of Boston, Massachusetts, are changing color about three days later than they used to. However, other scientists disagree with the global warming theory. Susan Rose said the leaves in her part of Colorado are changing “right on schedule.” But the leaves in other parts of that state are running a little late. “The lateness in the mountains may have something to do with the really warm late summer and early fall,” she said. “But I’m afraid that’s just a guess.”
【小题1】According to Susan Rose, _____.
| A．the fall colors are always in leaves |
| B．leaves make chlorophyll all the seasons |
| C．leaves’ changing color have nothing to with the weather |
| D．leaves begin changing color because they start making chlorophyll |
| A．reduces | B．increases | C．lasts | D．appears |
| A．genetic background | B．dry weather |
| C．global warming | D．low temperature |
| A．why leaves change color at fall |
| B．leaves change color at different time |
| C．the effects of the global warming on plants |
| D．different opinions on the lateness of leaves’ changing color |