摘要：What is the second paragraph mainly about? A. Some animals and plants cannot live without each other. B. Some animals and plants cannot develop their friendship easily. C. Some plants eat each other. D. Some animals live better together. 实战演练答案详解 缤纷自然篇 Passage 1 [答案与解析]这篇短文讲述了某些生物的迁移这一自然现象.并分析了迁移的原因.科学家们最近又研究了龙虾海底成群结队迁移的现象.它们选择在每年天气不好的季节里进行迁移.其中的原因及迁移的目的.科学家尚未弄清楚.
Most animals only have animals of a different kind for food．But sometimes two kinds of animals come together in a partnership(伙伴关系)which is good for them．You may have noticed some birds on the backs of sheep．This is not because they want a ride, but because they find easy food in the parasites(寄生虫)on sheep．The sheep let the birds do so because they can stop the parasites from troubling them．So though they can do with it by themselves, they can do better together with each other．
Sometimes an animal has a plant partner．The relationship develops until the two partners cannot do without each other．This is so in corals of the sea．Inside their bodies they have very small plants, which act as “cleaners”, taking the useless things from the coral and giving oxygen in return．That is what the animal needs to live．If the plants are killed, or are even kept from receiving light so that they cannot live as usual, the corals will die．
(1)
Some birds like to sit on a sheep because ________．
[ ]
A．
they can eat its parasites
B．
they enjoy traveling with the sheep
C．
they can’t live without its parasites
D．
they want to find the warm place
(2)
The underlined word “they” in the first paragraph means ________．
[ ]
A．
birds and parasites
B．
birds and sheep
C．
parasites and sheep
D．
birds, parasites and sheep
(3)
We learn from the passage that corals need plants for ________．
[ ]
A．
friends
B．
light
C．
food
D．
oxygen
(4)
The Chinese for the word “oxygen” is ________．
[ ]
A．
氧气
B．
空气
C．
废气
D．
二氧化碳
(5)
What is the second paragraph mainly about?
[ ]
A．
Some animals and plants cannot live without each other．
B．
Some animals and plants cannot develop their friendship easily．