Of all living creatures on earth, insects are the most plentiful. Some　 36　 are very useful to man, for example, bees,　 37　 we get honey and wax, and silkworms, which　 38　 us with silk. Other varieties,　39　, are extremely harmful, and do a great　 40　 of damage, especially to crops. Locusts （蝗虫） are perhaps the most dangerous of all,　 41　 they will eat almost any green　 42　 , and when millions of them　 43　 on cultivated land（耕地）they soon leave it　 44　. In some countries they are the farmer’s　 45　 enemy. Another nuisance is the common　 46　 , not only because it　 47　 us indoors and out - of- doors, but because it spreads diseases.
　　Scientists have given much time and　 48　 to the study of insects. It needs the most careful and　 49　 observation. Thanks　 50　 their discoveries we now know almost all　51　is to be known about the habits of these hardworking insects, bees and ants, which live in　52　better planned in some ways than our　　53　 . But the most valuable work has been done in trying to give　 54　 to men, animals and crops from the　 55　 which insects cause.
　　36．A. members  B. forms  C. qualities  D. varieties
　　37．A. by which  B. from which  C. of which  D. in which
　　38．A. give  B. produce  C. offer  D. supply
　　39．A. however  B. meanwhile C. therefore  D. what's more
　　40．A. majority  B. number  C. amount  D. quantity
　　41．A. and  B. for  C. if  D. when
　　42．A. grass  B. field  C. fruit  D. plant
　　43．A. settle  B. attack  C. pass  D. cross
　　44．A. bare  B. nothing  C. empty  D. untouched
　　45．A. hardest  B. greatest  C. serious  D. wildest
　　46．A. insect  B. creature  C. fly  D. enemy
　　47．A. dislikes  B. bites  C. worries  D. hates
　　48．A. understanding  B. ideas  C. comprehension  D. thought
　　49．A. serious  B. patient  C. curious  D. long
　　50．A. for  B. of  C. to  D. with
　　51．A. that  B. which  C. there  D. what
　　52．A. societies  B. crowds C. teams  D. organizations
　　53．A. world  B. nation  C. selves  D. own
　　54．A. help  B. protection  C. living  D. defense
　　55．A. injury  B. wound  C. sickness  D. ruin