下列各项中,属于丙烯制冷压缩机停车联锁动作的有()。
A、进出口电动阀关闭
B、最小流量返回打开
C、喷淋关闭
D、危急切断阀关闭
参考答案:A, B, C, D
He ______ in Shanghai University for four years before he ______ Beijing.
A.studied, had gone
B.had studied, went
C.has studied, goes
D.had studied, had gone
杀灭物体上所有微生物的方法称为( )
A.无菌操作
B.无菌
C.防腐
D.灭菌
E.消毒