题目内容
Every thing living on earth--each plant and animal--needs other living things. Nothing lives alone. Most animals must live in a group, and even a tree or a plant grows close together with others of the same kind. Sometimes one living thing hunts another, one eats and the other is eaten. Each kind of life eats another kind of life in order to live, and together they form a food chain. Some food chains are simple, others are complicated. But all have. two things in common--all food chains began with the sun, and all food chains become broken up if one of the links disappears.
All life depends on energy from sunlight. Only plants can use this energy directly. Their leaves are little factories that use sunlight to make food from water and things in the soil and air.
Plants in turn feted all other living things. Animals can only use the sun's energy after it has been changed into food by plants. Some animals feed directly on plants, others eat smaller animals. Meat-eating animals are only eating plants indirectly.
What about human beings? We are members of many food chains. We eat wheat, rice, vegetables, fruit and so on. We also eat meat and drink milk. This means the sun's energy passes through plants to animals before it reaches us.
Nature is a great thing. Any food chain always produces enough for each of its members if it is left alone. When there isn't enough food for any link in the chain, some of its members die off. So the balance is always kept.
But men often break up the food chain and do great harm net only to one plant or animal, but also to all the links in the chain. People make seas and rivers dirty. They destroy whole forests and kill many kinds of wild animals birds. When a river becomes dirty, the fish cannot be eaten. Men eat the fish and get strange diseases. In some places men have no fish to eat any more because the fish have died off. Each form of life is linked to all others. Breaking, the links puts all life in danger.
(1) How does everything living on earth live?
[ ]
A．Each plant can live alone.
B．Each animal can live alone.
C．Everything living on earth cannot live without needing other living things.
D．If living things want to live they must kill each other.
(2) How do all food chains break? All food chains are broken if ________.
[ ]
A．one kind of animal is eaten up
B．one kind of plant is destroyed
C．one kind of animal eats another
D．one of the links is destroyed
(3) How is food for plants made? Food for plants is made ________.
[ ]
A．from water
B．from the air in the sky
C．from the soil
D．from water and things in the soil and air
(4) Which living things can use energy directly?
[ ]
(5) Why is all life in danger? Because ________ break up the food chains.
[ ]
解析：
各地期末复习特训卷系列答案
小博士期末闯关100分系列答案
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||