小儿能抬头后能坐,之后能走是遵循了下列哪项发育顺序()
A.由上到下的顺序
B.由近到远的顺序
C.由粗到细的顺序
D.由低级到高级的顺序
E.由简单到复杂的顺序
参考答案:A
— Why on earth didn't you answer the phone?
— I'm terribly sorry, but the doorbell _____, too. [ ]
A. is ringing
B. rang
C. was ringing
D. has rung
反击式水轮机尾水管,增加水轮机的水头损失,从而降低了水轮机的效率。