以下关于切削液润滑作用说法正确的是()。
A、增大切削过程中摩擦
B、增大切削阻力
C、提高表面质量
D、降低刀具耐用度
参考答案:C
脐带中的血管有()
A.5根
B.4根
C.3根
D.2根
E.1根
根据句意及所给首字母提示,写出单词。
1. In China people eat with c _____ .
2. Don't s _____ your chopsticks into potatoes. It's not a good habit.
3. You should learn to face the c _____ in your life.
4. Different countries have different table _____.