若是2MHz声波用于检查人体软组织,则其波长接近()。
A.1/2mm
B.1/2cm
C.3/4mm
D.2mm
E.2cm
参考答案:C
下列各句均有一处错误,请找出并改正。
1.After a few minutes he came to myself and said, "Don't worry,I'm OK."______
2.Xiao Ming,don't play the water in the bottle.______
3.After the accident he lay on the road and almost couldn't breathe_______
4.Shall we go out for a walk after the lunch?_______
5.He went to work on foot instead driving his car.________
汽缸检修后,汽缸回装前对缸体内应做哪些准备工作?