液压泵的工作压力取决于自身的结构,与外界负载无关。()
参考答案:错
---How long has the train been away?
---Sorry. I don’t know. By the time I got here, the train ________.
A.has left
B.was leaving
C.has been away
D.had left
The summer vacation will begin next week. David to stay with us.[ ]
A. will be coming
B. comes
C. came
D. is coming