It was a difficult time, but we never _______ hope. [ ]

A. put up

B. gave up

C. picked up

D. used up

车削M36×2的内螺纹，工件材料为45钢，则车削内螺纹前的孔径尺寸为（）mm。

A．34

B．33.9

C．33.835

D．36