The other day,my friend John drove his car down the street at _ was a dangerous speed

问题描述:

The other day,my friend John drove his car down the street at _ was a dangerous speed
The other day,my friend John drove his car down the street at _ was a dangerous
A.as B.which C.what D.that
如果题目是The other day,my friend John drove his car down the street at____I thought was a dangerous 毫无疑问是选 C ,但如果没有那个I thought 、选B吗

问题有深度.I though为插入语,分析句子成分时通常忽略.所以无论有无都选C.
本句中,_ was a dangerous做at宾语从句,从句中缺主语,所以用what.which通常用在后面有范围时.如:后有A or B