问题补充:
The speed Tom drives his car is too high.
A. in which
B. at which
C. at that
D. in what
答案:
A. in which
(答案→)B. at which
C. at that
D. in what
解析:考查定语从句中关系词与介词的连用。定语从句中关系词前面的介词有3个来源:先行词的固定搭配,定语从句中的固定搭配:句子的语义;本题的先行词与介词at是固定搭配。at the speed of以…的速度;句意:Tom开车的速度太快了。故B正确。