转载机主要组成部分有()。
A.行走部
B.闭锁装置
C.机头传动部
D.刮板
E.链条
参考答案:A, C, E
无效腔容量加倍时,肺通气/血流比值将
A.加倍 B.减半 C.增大,但不到加倍D.减小,但不到减半 E.不变
—Hi, James. There is someone _______ for you at the school gate.
—It may be my mother. She comes to see me. [ ]
A. waited
B. waiting
C. to wait