加密、解密、压缩、还原等一般在（）进行。 A.传输层 B.会话层 C.表示层 D.应

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

胸外心脏按压的恰当按压部位是（）

A.胸骨上、中1／3交界处

B.胸骨下1／2

C.胸骨左缘第4肋间

D.胸骨中、下1／3交界处

E.胸骨左缘第4肋间腋中线上

在（）情况下，必须检测易燃、有毒有害气体或氧气的含量？

A.动火作业

B.设备内作业

C.聚合反应车间

D.进入设备内动火

E.设备检修指挥部

应急预案演练的原则不包括（）。

A.结合实际，合理定位

B.着眼实战，讲求实效

C.精心组织，确保安全

D.统筹规划，厉行简便

关于离合器自由行程，说法不正确的是（）。

A.可通过链轮来调整离合器自由行程

B.可通过钢索上的螺母来调整离合器自由行程

C.离合器自由行程是指从握住握把开始到感觉出钢索的抵触力大时，握把外端移动的距离

D.离合器自由行程为10-20mm