Of all living creatures on earth, insects are the most plentiful. Some 1 are very useful to man, for example, bees, 2 we get honey and wax, and silkworms, which 3 us with silk. Other varieties, 4 , are extremely harmful, and do a great 5 of damage, especially to crops. Locusts are perhaps the most dangerous of all, 6 they will eat almost any green 7 , and when millions of them 8 on cultivated land they soon leave it 9 . In some countries they are the farmers’ 10 enemy. Another nuisance is the common 11 , not only because it 12 us indoors and out-of-doors, but because it spreads diseases.
　　Scientists have given much time and 13 to the study of insects. It needs the most careful and 14 observation. Thanks 15 their discoveries we now know almost all 16 is to be known about the habits of these hardworking insects, bees and ants, which live in 17 better planned in some ways than our 18 . But the most valuable work has been done in trying to give 19 to men, animals and crops from the 20 which insects cause.
1．A．members            B．forms        C．qualities           D．varieties
2．A．by which            B．from which     C．of which           D．in which
3．A．give                B．produce        C．offer              D．supply
4．A．however             B．meanwhile     C．offer             D．supply
5．A．majority             B．number        C．amount           D．what’s more
6．A．and                 B．for            C．if                D．when
7．A．grass               B．field          C．fruit              D．plant
8．A．settle               B．attack         C．pass              D．cross
9．A．bare               B．nothing        C．empty             D．untouched
10．A．hardest            B．greatest        C．serious            D．wildest
11．A．insect              B．creature       C．fly               D．enemy
12．A．dislikes            B．bites          C．worries           D．hates
13．A．understanding       B．ideas           C．comprehension      D．thought
14．A．serious            B．patient        C．curious           D．long
15．A．for                B．of            C．to                D．with
16．A．that               B．which        C．there             D．what
17．A．societies            B．crowds        C．teams             D．organizations
18．A．world              B．nation       C．selves             D．own
19．A．help              B．protection    C．living             D．defense
20．A．injury              B．wound       C．sickness            D．ruin