永磁操作机构具有()等优点。
A、结构简单
B、可靠性高
C、价格低
D、耐磨损、机械寿命长
参考答案:A, B, D
— It is raining hard. Will you go to your friend's birthday party?
— I promised him to go, but the heavy rain really places me in a ______. I'm not sure whether I will go
or not. [ ]
A. disadvantage
B. conclusion
C. dilemma
D. challenge
以太网是( ) 的典型。
A.总线网
B.FDDI
C.令牌环网
D.星形网