细牙螺纹的特点是（）。
A.传动效率高
B.承受单向压力大
C.联接强度高，自锁性好
D.适用于污物接触较多的地方
参考答案：C
用所给词的适当形式填空。
1. You (can) try to do it.
2. He spent one hour (do) his homework.
3. I saw her (play) when I was eight.
4. She became a _ (skate) champion when she was ten.
5. He is a great __ (piano).
6. What can I do (become) famous?
7. How old were you when you started (learn) English?
8. He (win) the first prize last year.
9. Yao Ming is an (usual) basketball player.
轧件温度升高时，变形抗力（）。
