it is that都有哪些句式，除了强调句之外

这是一个主语从句.而It's .that是强调句
（1）主语从句.
It is important that students today master English.
It is reported that China will send up a series of spaceships in the 21st century.
It is a rule that everyone should obey the State’s laws.
It happened that they were out visiting their friends.
可以看出,此类主语从句的句子成分无论是主语、谓语、宾语,还是各种状语都是完整的,并且不能称到“It is…”结构中去.这就是判别主语从句的基本点.
（2）强调句.
先举一个重点成分句：昨天我在书店看见了他.I saw him at the bookstore yesterday.
现将此句变成分别突出主语、宾语、地点及时间状语的强调句：
A、It was I that/who saw him at the bookstore yesterday.
B、It was him that I saw at the bookstore yesterday.
C、It was at bookstore that I saw him yesterday.
D、It was yesterday that I saw him at the bookstore.