电雷管与火雷管的根本*区别在于增加了（）
A.电力点火装置
B.缓燃剂
C.加强帽
参考答案：A
Much to our surprise, his new book became an___ _ success. [ ]
A. instant
B. instructive
C. interesting
D. inexpensive
无菌盘铺好后有效时间不超过（）
A.4h
B.5h
C.6h
D.7h
E.8h
