All living things on the
earth need other living things to live with. Nothing lives 36 . Sometimes one living thing
kills 37 . Each kind of life eats
another kind of life 38 live, and together they form a food chain(食物链). Some food chains are simple, while others are not.
But 39 food chains begin with the sun, and all
food chains become 40 if one of the links disappears.
All life needs sunlight to
live on. But only plants can use 41 directly(直接地). They
make food from sunlight, water, air and so on. Animals can only use the sun’s
energy 42 it has been changed into food by plants.
Some animals feed directly on plants. Others eat smaller animals. Meat-eating
animals are only 43 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. But 44 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 45 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.
36. A. alone
B. lonely
C. together
D. happily
37. A. other
B. the other C.
another
D. the others
38. A. for
B. so that
C. and
D. in order to
39. A. any
B. all
C. some
D. most
40. A. better
B. broken
C. stronger
D. nicer
41. A. moonlight B. laser
light
C. sunlight
D. bright light
42. A. after
B. before C. until
D. by the time
43. A. making
B. catching C.
eating
D. feeding
44. A. sunlight B.
animals
C. plants
D. people
45. A. can
B. cannot
C. must
D. needn’t