The other day, my father drove his car at I thought was a dangerous speed.
A. as
B. that
C. which
D. what
网友回答
A. as
B. that
C. which
(答案→)D. what
解析：考查宾语从句。I thought是插入语，可以省略。What I thought was a dangerous speed是介词at的宾语，what在句中做主语。句意：前一天，我的父亲以一个我认为非常危险的速度开车。