_____ is no good always complaining about life. At least, we are living.

[       ]

A. It

B. There

C. This

D. That

封孔下木塞时，（）用异径接头直接下压木塞，以防超过木塞而卡住钻具。

A、不准

B、可以

C、随时可以

D、禁止