串级控制系统的投用,目前较为普遍的是采用()的投用方法。
A、先副回路后主回路
B、先主回路后副回路
C、主、副回路同时投用
D、只投用副回路
参考答案:A
预防伤口感染的主要措施是()
A.充分引流
B.及时、彻底清创
C.伤口内用碘酒、酒精消毒
D.伤口尽量缝合
E.主要依靠大剂量抗生素
— Hi, Tom. Any idea where Jane is?
— She _____ in the classroom. I saw her there just now. [ ]
A. shall be
B. should have been
C. must be
D. might have been