All living things on the earth need other living things to live with. Nothing lives  1  . Sometimes one living thing kills    2   . Each kind of life eats another kind of life     3    live, and together they form a food chain(食物链). Some food chains are simple, while others are not. But    4     food chains begin with the sun, and all food chains become    5    if one of the links disappears.
All life needs sunlight to live on. But only plants can use    6    directly(直接地). They make food from sunlight, water, air and so on. Animals can only use the sun’s energy    7     it has been changed into food by plants. Some animals feed directly on plants. Others eat smaller animals. Meat-eating animals are only   8 plants indirectly.
What about human beings? We are members of many food chains. We eat wheat, rice, vegetables, fruits and so on. We also eat meat and drink milk. But   9     often break up the food chains. They kill wild animals. They also make rivers, lakes and seas dirty. When these rivers, lakes and seas are polluted, the fish in them    10   be eaten. If people eat the fish, they will get strange diseases.
Each form of life is linked to all the others. Breaking the links puts all life in danger.

A．alone B．lonely C．together D．happily

A．other B．the other C．another D．the others

A．for B．so that C．and D．in order to

A．any B．all C．some D．most

A．better B．broken C．stronger D．nicer

A．moonlight B．laser light C．sunlight D．bright light

A．after B．before C．until D．by the time

A．making B．catching C．eating D．feeding

A．sunlight B．animals C．plants D．people

A．can B．cannot C．must D．needn’t