强调句型必须强调一个成分而非单词，公式是：it is/was + 被强调部分 + that + 句子剩下部分，例如，句子I saw your friend John at the party yesterday的主语、宾语、状语都可以强调，但是不可以强调谓语、表语。
强调主语:
It was I that saw your friend John at the party yesterday.
强调宾语:
It was your friend John that I saw at the party yesterday.
