is a good idea to improve our English by singing English songs. A. This B. That C. It

问题补充：

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

A. This B. That C. It

答案：

解析：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。