题目
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 favor 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.
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.
第1题
第2题
第3题
第4题
A.smell
B.spark
C.steam
D.smoke
第5题
A.symptoms
B.highlights
C.indicators
D.symbols
第6题
was a veritable real treasure-house which extended from Maine all the way down to Georgia.
请将上面这段话翻译成中文,谢谢!
第7题
A.to show he is already thinking about the topic from an anthropological perspective
B.to emphasize similarities between feathers of rain forest birds and coastal birds’ feathers
C.to give an example of collaboration between two societies
D.to compare the means of transportation used by ancient Peruvian to those used today.
第8题
A.A.all living things on the earth depend on the sun for their food
B.B.a forest looks dark in winter because it absorbs solar energy
C.C.only 0.023 of the energy from the sun is made use of on the earth
D.D.greenhouse gases allow heat energy to escape from the earth" s surface
第9题
A.the deforestation of the Amazon
B.the destruction of biodiversity
C.the desertification of the Amazon
D.the rare species of birds
第10题
It can be inferred from the last paragraph that scientists().
A.are puzzled by the mystery of forest pollution
B.feel relieved by the use of unleaded gasoline
C.still consider lead pollution a problem
D.lack sufficient means to combat lead pollution
第11题
Why are the lions in the Git Forest especially vulnerable to disease?
A.They are physically weaker than the African lions.
B.They are small in size.
C.They do not have enough to eat.
D.They have descended from a dozen or so ancestors.
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