制式爆炸装置主要从爆炸装置的()来分类,主要有机械发火引信装置、化学引信和电发火引信等。
A.引信
B.性能
C.基本构造
D.发火原理
参考答案:C, D
Susan's father was pretty anxious because he ______ his notebook on the bus. [ ]
A. dropped
B. fell
C. broke
D. showed
介导体液免疫的是()
A.LAK细胞
B.T细胞
C.K细胞
D.B细胞
E.NK细胞