江南科技馆有一种神奇的装置，如图所示，借助该装置，小明仅用150N的拉力就提起了

流行病学研究的对象是

A．病人

B．非病人

C．人群

D．个体

E．病原携带者

用and, but 或or 完成句子。

1. Would you like some coffee _____ tea?

2. His father is tall _____ his mother is short.

3. Let's go _____ play basketball.

4. Maria likes thrillers, _____ she doesn't like cartoons.

5. He often helps me _____ I often help him.

厕浴间和有防水要求的建筑地面必须设置（）

A.防水层

B.走坡层

C.保温层

D.隔离层

ACTH分泌最低的时间在

A．入睡时
B．零点
C．清晨
D．上午

磨煤机热风自动需要哪些测量信号？