根据螺纹牙型的不同，可分为（ ）螺纹、（ ）螺纹、（ ）螺纹和（ ）螺纹。

A. She wants the man to go by himself.
B. The policeman maybe know the way.
C. The park is near the police station.
D. The man should ask the policeman to go.

A. They missed the train.
B. The train had not left yet when the twopeople got to the station.
C. They were looking for each other all the time.
D. They could go back home that day.

A. One
B. Four
C. Two
D. Three