Most animals have little connection with animals of different kind, unless they hunt t
Sometimes an animal has a plant partner. The relationship develops until the two partners cannot manage without each other. This is so in the corals (珊瑚 ) of the sea. In their skins they have tiny plants act as "dustman", taking some of the waste products form. the corals and giving in return oxygen which the animal needs to breathe. If the plants are killed, or are ever prevented from lighting so that they cannot live normally, the corals will die.
1、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 traveling with the sheep
D、 they find the position most comfortable
2、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
3、What does the second paragraph mainly discuss? ()
A、Some animals and plants depend on each other for existence.
B、 Some animals and plants develop their relationship easily.
C、 Some plants depend on each other for foo
D、 Some animals live better together.
4、What does this article talk about? ()
A、Two kinds of animals for a partnership.
B、Most animals only have connection with animals.
C、The connection between the living things.
D、Corals have some connection with plants.