完形填空。 There are seas, lakes and forests
题型：完形填空
问题：
| 完形填空。 | |||
| There are seas, lakes and forests on the earth. There are cities, towns and farms, too. All these things are environments. The environment is everything around you. It can be living (有生命的), like a forest. It can be non-living (无生命的), 1 a rock or a mountain. No living thing can live alone. Every living thing depends (依赖于) on other things in its environment. When something 2 , it affects (影响) something else. If a non-living; thing like water becomes 3 to find, plants will be affected. If all plants 4 , the animals that eat plants will be affected. Weather, such as temperature, wind and rain, can change an environment. 5 can change an environment, too. Some things that people do cause no change or only a small change in the environment. For example, people can walk through the forest and just travel around. They can cut down only a few trees and 6 change the environment very much. On the other hand, some things that people do cause 7 changes. Sometimes they can change a whole environment by cutting down a forest. Not all changes are bad. If we cut down a forest to build houses or plant crops, this may not be bad. But what would happen if we cut down all trees in all forests or if we didn't 8 them and plant something else? It is clear that people are able to change an environment. This is why it is important to think about the changes before we make 9 . Let's work together to 10 it clean and healthy. | |||
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的空气柱。已知大气压强为l0汞柱髙。如果使玻璃管绕B点在竖直平面内顺时针缓慢地转动至BC管水平，求此时AB管内气体的压强为多少汞柱高？管内封入的气体可视为理想气体且温度不变。
