We saw several natives advancing towards our party, and one of them came up to us, ______ we gave some bells and glasses.

A. to which         B to whom             C. with whom      D. with which 

钻井过程中，阻力突然增大，后又突然减小，可能是发生了（）故障。

A、卡钻

B、钻具折断

C、跑钻

D、以上均不可能发生