Question

【題目】 Do trees stop growing? The answer is both yes and no. The trunks (樹干) of trees keep getting wider,【1】. But, in fact, trees do stop growing in height. You can notice the similar height of the trees when you see a stand of trees of the same species (物種).

Just like people, the slowing in the growth of trees is related to their age. Trees grow more slowly as they age. At a certain age, they necessarily stop gaining height.【2】. But by the time the tree reaches 90 years of age, its growth has slowed to about half a meter--about a foot and a half- a year. By the time the tree is 150 years old, height growth has almost stopped, even though the tree may live another 100 years.

Some scientists suggest that tree cells ( 細(xì)胞 ) are like animal cells: that is,【3】. If a tree's cells stop dividing, then it stops getting taller. Another idea is that a tree's height is limited by the way it carries water from its roots to its leaves. Inside a tree, water moves upward, pulled towards the leaves. Some scientists put forward an idea that once a tree reaches old age and is tall enough, the downward pull of gravity (重力) makes it more and more difficult for the tree to pull the water all the way to its upper branches ( 樹枝 ) and leaves.

So do trees stop growing? They do, and they don't. At some point, their height is more or less fixed at the same height as other trees of that kind.【4】.

A.and trees add new rings year after year

B.the height growth will keep going on for centuries

C.they have to stop growing after a certain number of divisions

D.But trees continue to add width to their trunks throughout their lives to put out new branches and sprout (生長; 發(fā)芽) leaves.

E.As a young tree, it might grow two to three meters or even about seven to ten feet every year

Answer 1

【答案】

【1】A

【2】E

【3】C

【4】D

【解析】

文章介紹了樹木是如何生長的。

【1】根據(jù)前一句“The trunks (樹干) of trees keep getting wider”意為“樹木的樹干越來越寬”可知樹木的年輪一年年增加。故選A。

【2】根據(jù)后一句“But by the time the tree reaches 90 years of age, its growth has slowed to about half a meter--about a foot and a half- a year.”意為“但是，當(dāng)樹長到90歲時(shí)，其生長速度已減慢到大約半米-大約一英尺半。”可知轉(zhuǎn)折詞前面提到的內(nèi)容必然與之相反，應(yīng)是樹木小的時(shí)候。故選E。

【3】根據(jù)后一句“If a tree's cells stop dividing, then it stops getting taller.”意為“如果一棵樹的細(xì)胞停止分裂，那么它將不再變得更高。”可知結(jié)論應(yīng)是樹木在分裂一定數(shù)量后停止增長。故選C。

【4】根據(jù)前一句“So do trees stop growing? They do, and they don't. At some point, their height is more or less fixed at the same height as other trees of that kind.”意為“那么樹木會(huì)停止生長嗎？他們有，但也沒有。在某些時(shí)候，它們的高度或多或少固定在與其他同類樹木相同的高度上。”可知，樹木會(huì)一直增長，前期是高度的增長，后期高度停止增長，看似沒有增長，其實(shí)是寬度在增長。故選D。