The global warming is more and more serious，for which human beings .
A. are blaming
B. are to blame
C. are going to blame
D. are to be blamed
网友回答
A. are blaming
(答案→)B. are to blame
C. are going to blame
D. are to be blamed
解析：
be to blame用主动形式表示被动含义，表示“应该受责备”。句意为：全球变暖越来越严重，在这个问题上人类应该受到责备。