【正文】
building B Most animals have little connection with animals of different kind, unless they hunt them for , however, two kinds of animals e together in a partnership(伙伴關(guān)系 ) which does good to both of may have noticed some birds sitting on the backs of is not because they want a ride, but because they find easy food in the parasites (寄生蟲 ) on sheep allow the birds to do so because they remove the cause of although they can manage without each other, they do better together. Sometimes an animal has a plant relationship develops until the two partners cannot manage without each is so in the corals (珊瑚 ) of the their skins they have tiny plants act as “dustman” , taking some of the waste products from the coral and giving in return oxygen (氧氣 ) which the animal needs to the plants are killed, or are even prevented from light so that they cannot live normally, the corals will die. 5. Some birds like to sit on a sheep because________. A. they can eat its parasites B. they depend on the sheep for existence C. they enjoy travelling with the sheep D. they find the position most fortable 6. The underlined word “they” in the last sentence of the first paragraph refers to________. A. birds and parasites B. birds and sheep C. parasites and sheep D. sheep, birds and parasites 7. It can be learnt from the text that the coral depends on the plant for________. A. fort B. light C. food D. oxygen 8. What does this article talk about? A. Two kinds of animals form a partnership. B. Most