All living things on the earth need other living things to live．Nothing lives alone．Most animals must live in a group, and even a plant grows close together with others of the same kind．Sometimes one living thing kills another, one eats and the other is eaten．Each kind of life eats another kind of life in order to live, and together they create a food chain(链条)．Some food chains are simple, while others are not．But all food chains begin with the sun, and all food chains become broken up if one of the links(链接)disappears．
All life needs sunlight to live on．But only plants can use sunlight directly．Plants are ‘factories'．They make food from sunlight, water and things in the soil(土壤)and air．Plants feed 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 humans? We are members of many food chains．We eat rice, vegetables, and fruits and so on．We also eat meat and drink milk．But we often break up the food chains．We kill wild animals and also make rivers, lakes and seas polluted．When these rivers, lakes and seas are polluted, the fish in them can not be eaten．If we eat the fish, we will get strange illnesses．
Each form of life is linked(关联的)to all others．Breaking the links puts all life in danger．
(1)
Which living things can use the sun's energy directly?
[ ]
A．
Animals．
B．
Plants
C．
Animals and plants．
D．
All living things．
(2)
Who often destroy the food chains?
[ ]
A．
Humans．
B．
Animals．
C．
Plants and animals．
D．
Humans and wild animals．
(3)
Which of the following would be the best title for this passage?
Most American children eat potatoes．But many children don't know what of the potato is the best for food．Take a knife and cut from the middle of the potato a piece as thin as paper．Hold the piece between your eyes and light．You will see that the potato has skin(皮)，an outside rim(边缘) and an inside part．The outside rim which is right under the skin of the potato，is the most valuable part of all．But this is often thrown away with the skin．Even the skin itself is better for food than the inside．When eating a cooked potato，if you choose the inside and leave the outside，you are throwing the best part of it．If you can't eat the whole potato，eating the outside rim and leaving the inside will do．
(1)
How many parts does the potato have?
A．It has only one part，outside rim．
B．It has two parts，skin and outside rim．
C．It has three parts，skin，outside rim and an inside part．
D．It has four parts，middle，skin，outside rim and an inside part．
[ ]
(2)
What is the best part of a potato?
A．Outside rim． B．Inside part． C．Middle． D．Skin．
[ ]
(3)
What should you eat first if you can't eat the whole potato?
A．Skin only． B．Inside． C．Outside rim． D．Part of it．
