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Questions 26 to 30 are based on the following passage:

The forest from which Man takes his timber is the tallest and most impressive plant community on Earth. In terms of Man's brief life it appears permanent and unchanging, save for the seasonal growth and fall of the leaves, but to forester it represents the climax of a long succession of events. No wooded landscape we see today has been forest for all time. Plants have minimum requirements of temperature and moisture and, in ages past, virtually every part of Earth's surface has at some time been either too dry or too cold for plants to survive. However, as soon as climatic conditions change in favour of plant life, a fascinating sequence of changes occurs, called a primary succession.

First to colonize the barren land are the lowly lichens, surviving on bare rock.

Slowly, the acids produced by these organisms crack the rock surface, plant debris accumulates, and mosses establish a shallow roothold. Ferns may follow and, with short grasses and shrubs, gradually form a covering of plant life. Roots probe even deeper into the developing soil and eventually large shrubs give way to the first trees. These grow rapidly, cutting off sunlight from the smaller plants, and soon establish complete domination—closing their ranks and forming a climax community which may endure for thousands of years.

Yet even this community is not everlasting. Fire may destroy it outright and settlers may cut it down to gain land for pasture or cultivation. If the land is then abandoned, a secondary succession will take over, developing much faster on the more hospitable soil. Shrubs and trees are among the early invaders, their seeds carried by the wind, by birds and lodged in the coats of mammals.For as long as it stands and thrives, the forest is a vast machine, storing energy and many elements essential for life.

26.What does the forest strike mankind as permanent?

A) The trees are in community.

B) The forest is renewed each season.

C) Man's life is short in comparison.

D) It is an essential part our lives.

27.What has sometimes caused plants to die out of the past?

A) Interference from foresters.

B) Variations in climate.

C) The absence of wooded land.

D) The introduction of new type of plants.

28.In a “primary succession', what makes it possible for mosses to take root?

A) The type of rock.

B) The amount of sunlight.

C) The amount of moisture.

D) The effect of lichens.

29.What conditions are needed for shrubs to become established?

A) Ferns must take root.

B) The ground must be covered with grass.

C) More soil must accumulate.

D) Smaller plants must die out.

30.Why is a “secondary succession” quicker?

A) The ground is more suitable.

B) There is more space for new plants.

B) Birds and animals bring new seeds.

D) It is supported by the forest.


短文大意:本文主要叙述人与自然的生态关系,地球上的森林是经过千百万年演变而存活下来的人类生态环境。那些我们今天所看到的光秃秃的大地过去曾是茂密的 森林。植物的生长与气候密切相关,一旦气候变得恶劣,植物便会灭绝。如果人类一味地乱砍乱伐,垦田开荒,那么地球上的生态环境就会遭到破坏,生物链就要发生改变。

26. 答 案C。【参考译文】森林对人类的冲击在什么方面是永久性的 ?【试题分析】本题为一般理解题,需要在字里行间找答 案。【详细解答】在这篇文章的第1段的第二句话,可以找到 C)是正确答 案。

27. 答 案B。【参考译文】有时候是什么造成从前的植物灭绝 ?【试题分析】本题考察对上下文的理解,需从字里行间找答 案。


28. 答 案D。【参考译文】在“初级演”中,什么使苔藓生根成为可能 ?【试题分析】本题为一般阅读理解题,需从段落的字里行间中找答案。【详细解答】第三段的第二句话中,作者提到了首先能在岩石上生存的植物是 lichen(地衣),然后在地衣生长之后,由于地衣的影响才能使moss(苔藓))的生长成为可能。

29. 答 案C。【参考译文】灌木稳固生长需要什么条件 ?【试题分析】同上。

【解答要领】在第三段的中间,只有在长过苔藓之后草木和 shrub(灌木)才能生长,因为已经固定相当一部分土壤,有利于植物生长,故选C)。

30. 答 案A。【参考译文】为什么“第二次演替”较快 ?【试题分析】同上。【详细解答】从第四段的中间,我们可以看出,根本的原因乃是土壤较为适宜。






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