对于活塞泵的启动,第一步需要做的是()
A.启动电机
B.打开进出口阀
C.调节流量
D.调节压力
参考答案:B
.
---Have you found your MP4 yet?
---Yes. It was in the classroom, rather than on the playground, ________we practiced dancing.
A.which
B.that
C.where
D.when
Do you think this skirt is too tight ______ the shoulders?
A.at
B.on
C.to
D.across