单选题 Life on land probably began about 430 million years ago, though it has existed in the water for perhaps as long as 3, 000 mil lion years. When we think of the first life on land, we probably think of strange animals coming out of the oceans, but, in fact, no animals could have been living if plants had not been on land first. Plants had to be on land before animals arrived. They supplied the first land animals with food necessary to live, since they are the only form of life that is able to get and store energy.
The first plants to exist out of the water were probably certain kinds of algae(海藻) which were followed by other plants that grew close to the ground near water and needed water in which to repro duce. Once the move to land had been made, however, evolution (进化) took place quickly. By the end of 100 million years, plants had developed their roots, and some developed tall tree like forms, since height was very important in competing for sunlight. About 300 million years ago, much of the world was covered with forests of huge trees. In most ways they were like modern trees. They had roots, leaves, wood, but mostly they had not developed seeds.

单选题 The main idea of the first paragraph is ______.
A. life on land probably began about 4, 300 years ago
B. the first animal on land came from oceans
C. there wouldn't be animals without plants
D. plants are the only form of life that is able to get and store energy

【正确答案】 C

【答案解析】ABD项都是第一段巾的内容，但都不是主要内容，如果没有看清楚题目中要求的main idea，这道题很有可能选错，因为ABD项都是第一段中的内容，如果看清楚题目中问的是主要内容，那么这道题并没有什么难度。第一段就是说明陆地上如果首先没有植物，动物将无法生存。因此正确答案应该是C。

单选题 Which of the following is true?
A. Algae have existed for more than 430 million years.
B. It is impossible that algae might be the earliest plant on land.
C. Plants get food from animals in the oceans.
D. Evolution began after animals appeared on land.

【正确答案】 A

【答案解析】这是一道综合性比较强的题日。必须从第一段和第二段综合考虑才能得出正确的答案。第一段中说：Life on land probably began about 430 million years ago(在4亿三千万年前陆地上才开始存在生命)第二段中说：The first plants to exist out of the water were probably certain kinds of algae(离开水中的生活环境的第一种植物可能是某种海藻类植物)通过这两句话我们可以得出结论：(第一个在陆地上存活的生命)海藻是在4亿三千万年前开始存在在陆地上的。而海藻存在于水中的时间肯定更长。所以海藻存在的时间肯定超过了4亿三千万年。所以本题的正确答案是A。

单选题 Plants with roots appeared about ______ million years ago.
A. 430 B. 300
C. 330 D. 100

【正确答案】 D

【答案解析】By the end of100 million years，plants had developed their roots(到了1亿年前的后牛段，植物已经形成了它们的根)从以上这句话可以看出，本题的正确答案应该是D.

单选题 According to the passage, the higher a tree grows, ______.
A. the stronger it becomes B. the more sunlight it will get
C. the thinner it will be D. the thicker it will be

【正确答案】 B

【答案解析】height was very important in competing for sunlight (高度对于得到更好的太阳光是非常重要的)从这句话可以看出，树木之所以要长的更高，是因为长的高可以获得更多的阳光，从而可以更利于它们的生长。

单选题 The first trees were like modern trees in most ways except that ______.
A. they do not have branches B. they do not have flowers
C. they do not have seeds D. they do not need sunlight

【正确答案】 C

【答案解析】but mostly they had not developed seeds．(但是大部分都还没有形成它们的种子)从这句话可以很容易看出木题的答案应该是C。