单项选择题

The first paragraph mainly tells us______.

A．why we don't feel air
B．why atmosphere is important to us
C．why there is air surrounding us
D．why there is air pressure
<上一题 目录 下一题>
热门 试题

单项选择题
Air moves under such conditions that______.
A．there is air pressure
B．the air is heavy
C．air pressure doesn't remain the same all the time
D．air comes up and down
单项选择题
What were the primary uses of the horse for early man
A．For food.
B．For power.
C．To make money.
D．To work for him.
相关试题