问题描述：
[单选]
When we say that two objects have relative motion， we mean（）．
A．the distance between them remains the same
B．the distance between them is changing
C．the position between them is not changing
D．their positions to the earth remain the same
参考答案：查看无
答案解析：无
☆收藏
答案解析：无
☆收藏
上一篇：Among the main propulsion units on board the ship with the same capacity， the lightest one is（）．
下一篇：The trouble-free life of an engine indicates（）．
- 我要回答: 网友(3.144.83.68)
- 热门题目: 1.船上常用的柴油机单缸停油措施 2.船舶停航，完车后应做哪些工作 3.船舶航行中，怎样进行柴油机的