阅读下列短文，从每题所给的A、B、C、D四个选项中，选出最佳选项。
All plant cells are capable of taking up water. Even dead ones do to a certain degree. Absorption of water by dead cell wall makes wood swell. In common land plants, the living cells of roots take up most of the water. Land plants without roots do exist, however. Those greenish-yellow lichens you see on tree trunks and on rocks you see in the high mountains have no roots. Half a billion years ago, when water plants started to invade the land, the first primitive land plants did not have roots; they were marsh plants.
Even among the flowering plants, one finds rootless forms. These flowering plants are the so-called higher plants because they evolved more recently and are thus considered higher on the evolutionary scale. In the Peruvian desert, there grows one of these rootless higher plants, a bromeliad. It is a relative of the pine apple. Even if this plant had roots, they would be of no use, because where the plant grows, it never rains. The plant gets its water only from the dew it collects at night, when its leaves cool off. Such rootless plants, of course, can be moved with ease, but they will only grow when they are placed out in the open. If they are placed too near the house, the radiation from the heat of the house prevents the leaves from cooling and so prevents dew from forming, and the plant dies. In the southern United States and in Puerto Rico, one sees bromeliads growing high above the streets in the insulation of electric wires. These plants obtain their water from rain, and the only soil they ever come in contact with is the dust that may blow on their leaves.
1. The living cells of roots of the land plants__________.
A. need most of the water
B. absorb most of the water
C. are not as useful as those of the leaves
D. absorb more water than is necessary for later use
[答案]
2. The lichen on tree trunks and on rocks___________.
A. can exist without leaves
B. cannot exist without roots
C. may be called higher land plants
D. can exist without roots
[答案]
3. A bromeliad __________.
A. is a relative of the lichen
B. has roots which are useless
C. is a type of flower plant for its lack of roots
D. keeps alive by absorbing the dew
[答案]
4. These rootless plants placed too near a house will die because ___________.
A. they are not accustomed to absorb a large amount of water
B. they are often moved by people from place to place
C. the plants near them take up most of the water
D. the radiation from the heat of the house prevent the forming of the dew
[答案]
5. The best title for the passage would be __________.
A. Primitive Plants and Higher Plants
B. The Water Intake of Plants
C. The Rootless Higher Plants
D. The Importance of the Dew
[答案]
