During the examination we are required to stay in our seats, keep our eyes on our work,      to anyone.

A．instead of speaking

B．rather than speak

C．and not to speak

D．but would not speak

使用力矩扳手的作用是使螺钉（）。

A、进一步紧固

B、便于紧固

C、达到规定的扭矩

D、不松动