Question

______ is a good idea to improve our English by singing English songs.

1. A.
   This
2. B.
   That
3. C.
   It

Answer 1

C
此题重点考查固定句型结构it is+adj+to do sth表示对某人来说做某事怎样。其中it是形式主语真正的主语是后面的动词不定式。故选C。