3．It is only during the last few years that man has generally realized that in the world of nature a balance exists （存在 ） between all forms of life．No living thing can exist by itself； it is part of a system in which all forms of life are joined together．If we change one part of the nature order，this will in turn almost certainly bring about changes in some other part．
The cutting down of forests reduces the supply of oxygen．The killing of weeds and insects by chemicals leads to the widespread poisoning （中毒） of animals and birds．The throwing of waste products into the ocean hurts life in the sea，while waste gases change the chemical balance of atmosphere and shut out some of the sun's necessary life-giving rays．
And so we could go on，adding more examples，until in despair （絕望） we might feel like giving up the struggle to control and keep within limits these harmful human activities．Man is very clever at changing the world around him to satisfy his immediate need，but he is not so clever at looking far ahead，or at thinking about what the future results of his action might be．Man may well destroy himself in his attempt （企圖） to be too ambitious （野心）．
21．The examples given in the second paragraph are evidences （證據） thatD．
A．it is during the last few years that man has generally known the balance of nature
B．there are some living things which can exist by themselves without change
C．all forms of life belong to a system in which all the parts can be changed for another
D．we cannot change one form of life without destroying the balance of nature
22．The last paragraph suggests that，in man's attempt to increase immediate benefits，A．
A．man often fails to think about his future results of his action
B．man is always too ambitious to planning distant future
C．man often feels that he will have to give up in despair
D．man is always anxious to control and keep his activities within limits
23．Which of the following statements is true？B
A．Cutting down woods does little harm to human beings．
B．Man has to pay much attention to the future results of his present action．
C．Oxygen comes from forests．
D．This passage tells us to try our best to get as much as possible immediately．
24．Which of the following is the best title of this passage？B
A．The Secret of Nature
B．The Balance of Nature
C．The Order of Nature
D．The Change of Nature．
分析 本文主要是關于環境保護，要人類維持自然平衡，呼吁我們要關注環保．
解答 21．D 推理題．根據文章內容，The cutting down of forests reduces the supply of oxygen．The killing of weeds and insects by chemicals leads to the widespread poisoning （中毒） of animals and birds．這些例子告訴我們不能破壞自然的平衡，否則會受到自然的處罰，結合選項，故D正確．
22．A考查細節理解題．根據文章And so we could go on，adding more examples，until in despair （絕望） we might feel like giving up the struggle to control and keep within limits these harmful human activities但是人類不是如此擅長向前看或不善于考慮他的行動可能帶來的結果，結婚選項，故A正確．
23．B 細節題．根據文章內容，Man is very clever at changing the world around him to satisfy his immediate need，but he is not so clever at looking far ahead，or at thinking about what the future results of his action might be．人類很聰明，可以改變現狀來滿足目前的需要．但是人類在長遠發展和現在這個行為可能對以后產生的影響這個方面卻不聰明了，由此可知，我們人類必須注意自己的行為對未來的影響．結合選項，故選B
24．B 主旨題．根據文章內容，主要是關于環境保護，要人類維持自然平衡，呼吁我們要關注環保．結合選項，故選B
點評 但是本文是一個人生感悟類閱讀理解，題目涉及多道細節理解題，做題時結合原文和題目有針對性的找出相關語句進行仔細分析，結合選項選出正確答案．推理判斷題也是要在抓住關鍵句子的基礎上合理的分析才能得出正確答案，切忌胡亂猜測，一定要做到有理有據
