所谓液压传动，就是以油液为工作介质传递能量，实现工作机构的变速和变力。
参考答案：对
下列说法正确的是（ ）
A．“坐地日行八万里”的地球可以视作质点
B．建立质点概念的物理方法是等效替代的方法
C．古代“刻舟求剑”故事中，刻舟求剑者的错误在于错选了参照系
D．第4 s末和第5 s初指同一时刻，在时间轴上二者对应同一点
用所给单词的适当形式完成句子。
1. Tom's father is ___ (two) as tall as him.
2. The oil now is even______(expensive) than before.
3. She was troubled because she had reached the ____ (weigh) of 180 pounds.
4. The______ (high) of the Qomolangma is 8,844 meters.
5. The heavy rain prevented us from ____ (come) in time.
