电梯的机械安全保护系统主要由( )等部件组成。
A.缓冲器
B.导轨
C.安全钳
D.门锁
参考答案:A,C,D
Was it not until you began to write ______ you should have remembered more words?
A.did you realize
B.that you realized
C.did you not realize
D.that you didn't realize
下列哪一项措施与防止浸润型肺结核传播无关()
A.接触患者时戴口罩、帽子、穿隔离衣
B.患者痰液用含氯石灰溶液搅拌静置2小时
C.病室每天用紫外线照射进行空气消毒
D.病室设纱门,室内喷洒杀虫药剂
E.病室通向走廊的窗子须关闭