The other day my brother drove his car down the street at I thought was a dangerous speed.
A. as
B. which
C. where
D. what
网友回答
A. as
B. which
C. where
(答案→)D. what
解析：考查宾语从句，此题考查作介词at的宾语从句，I thought为插入语，所以从句中就缺少了主语，故用关系词what，几天前我的哥哥在大街上行驶，以一种我认为是非常危险的速度。故选D。