It is 可用于強調句、定語從句、主語從句等多種句型，舉例如下：
It is(was)that句型,It is+被強調成分+that+句子剩余部分（強調句）：
可以分別用來強調主語、賓語、地點狀語和時間狀語。如：
It was he who(that)read three books in the library yesterday.(強調主語)
是他昨天在圖書館讀了三本書。
It was in the library that he read three books yesterday.(強調地點狀語)
他昨天是在圖書館里讀了三本書。
It is+名詞+定語從句：
It was the day my grandmother was angry.
那一天我外婆生氣了。
It is +名詞/形容詞+不定式主語：
It做形式主語，句子真正的主語是不定式。
It was a pleasure to draw pictures.
畫畫是一種享受。