It is you as well as your wife that your son's bad performance at school.
A. is to be blamed for
B. are to be blamed for
C. are to blame for
D. is to blame for
网友回答
A. is to be blamed for
B. are to be blamed for
(答案→)C. are to blame for
D. is to blame for
解析：题干中用了强调结构，主语是you，所以谓语要用复数；be to blame是固定句式，用主动形式表示被动意义。