问题补充：
seems difficult who broke the window.
A. This;to find out
B. It;to find out
C. That;finding out
D. It;finding out
答案：
A. This;to find out
B. It;to find out
C. That;finding out
D. It;finding out
解析：
试题分析: 句意: 找出谁打破窗户似乎很困难。It seems +adj+to do做某事似乎……的，固定句型，it 为形式主语，to do不定式做真正主语，故答案选B.
