疏水扩容器排水管上倒“U”型水封的作用?
参考答案:
倒“U”形水封和扩容器构成连通管,使扩容器保持一定的水位。
Jenny likes ___________ in the wind.[ ]
A. plays
B. played
C. to play
D. play
每个公民应该多长时间做一次健康体检?