—Who has broken the window in my room?

—Who else      it but your naughty son!

A．could do

B．could have done

C．might do

D．must have done

下列哪些情况不准下钻（）

A、钻杆均直径均匀磨损达3mm

B、每米弯曲超过3cm

C、丝扣严重磨损、松动或其他明显变形

D、钻具接头、接箍合格