Is this the very reason _________ at the meeting for the carelessness and pride in his work?

Is this the very reason _________ at the meeting for the carelessness and pride in his work?

A.he explained

B.what he explained

C.how he explained

D.why he explained

答案及解析： A

此题具有迷惑性，一看到reason很多同学认为选择D项。解题的关键在于reason作explain的宾语。因此选择A。