Private cars are required to take turns off roads one out of five weekdays ____the

traffic pressure.

A．to reduce

B．reducing

C．reduce

D．reduced

根据接头、坡口以及焊缝结合形式的不同，可分为（）等。

A、对接焊缝

B、角焊缝

C、塞焊缝

D、端焊缝