一对齿轮的传动比就是从动轮与主动轮的齿数比。
参考答案：对
锐角三角形底边上的高可以把它分成两个______角三角形．
Introduce yourself to others. 向别人介绍你自己吧！
1. What's your name?
2. How old are you?
3. What is your favourite school work?
4. What do you like to do?
5. What is your favourite dessert?
