强调句

　　强调句型由“It is (was) + 被强调的成份(主语、宾语、状语)+ that”构成，当被强调的主语表示人时，that可以用who替代，谓语在人称和数上应与主语保持一致。

　　It is he who speaks English fluently.

　　It was not until midnight that he went to sleep last night.