To be honest，it is Jack as well as his two classmates that for the broken vase.
A. is to blame
B. is to be blamed
C. are to be blamed
D. are to blame
网友回答
(答案→)A. is to blame
B. is to be blamed
C. are to be blamed
D. are to blame
解析：A 考查主谓一致及blame的用法。当as well as连接两个名词作主语时，谓语动词的数根据as well as之前的名词判断，有类似用法的词还有：with，together with，rather than，besides等。sb.be to blame是一种固定表达，意为“……该受责备/惩罚”。