滚动轴承的优点是什么?
参考答案:
滚动轴承依靠主要元件间的滚动接触支承转动零件,故以滚动磨擦代了滑动轴承中的滑动磨擦,因而具有摩擦阻力小,功率消耗少,启动容易等优点。
用所给单词的正确形式填空:
1. There are four ________ (tomato) in the drawer.
2. Jeff likes _______ (strawberry) very much.
3. Are these _________ (you)oranges?
4. Sonia _______ (have) a sports collection.
5. She _______(like) bananas.
6. I _______( not like) math.
7. She ________(play) sports every day.
知识就是一种力量是谁的名言?()
A、拉伯雷
B、但丁
C、培根
D、哈维斯