Question

Last Sunday morning, my dear brother drove his car down the street at ________ I thought was a very dangerous speed．

[　　]

A．

as

B．

which

C．

what

D．

that

Answer 1

答案：C
解析：

本句的中心结构是“my brother drove his car at a very dangerous speed”。a very dangerous speed是名词短语，what在语法上相当于the speed that引起从句，I thought作为插入语。答案是C。