Question

【题目】 Do trees stop growing? The answer is both yes and no. The trunks (树干) 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 (物种).

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 ( 细胞 ) 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 ( 树枝 ) 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 (生长; 发芽) 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】

文章介绍了树木是如何生长的。

【1】根据前一句“The trunks (树干) of trees keep getting wider”意为“树木的树干越来越宽”可知树木的年轮一年年增加。故选A。

【2】根据后一句“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.”意为“但是，当树长到90岁时，其生长速度已减慢到大约半米-大约一英尺半。”可知转折词前面提到的内容必然与之相反，应是树木小的时候。故选E。

【3】根据后一句“If a tree's cells stop dividing, then it stops getting taller.”意为“如果一棵树的细胞停止分裂，那么它将不再变得更高。”可知结论应是树木在分裂一定数量后停止增长。故选C。

【4】根据前一句“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.”意为“那么树木会停止生长吗？他们有，但也没有。在某些时候，它们的高度或多或少固定在与其他同类树木相同的高度上。”可知，树木会一直增长，前期是高度的增长，后期高度停止增长，看似没有增长，其实是宽度在增长。故选D。