he failed not because he isn't clever ( )he didn't work hard

问题描述:

he failed not because he isn't clever ( )he didn't work hard
A.but B.but for C.but because
抱歉``我选的是A 但答案给的是C 是不是有对称的关系`

not... but... 不是...而是.
两个because并列
but for 的意思是: 如果不是.的话