主语从句就是在句中作主语，主语从句的位置与陈述句中主语位置相同的，统观主语从句的考核占有相当比重，下面和小编具体来看一下that引导的主语从句吧！
1.that在句中不做成分。当主语从句位于句首时，不能省略：
That he likes books of this kind is very interesting.= It’s very interesting (that)he likes books of this kind.
这是用的最多的一种主语从句,但把这种主语从句放在句首是很少的,只是为了强调或谓语较长时才这样安排.例如：
That?prices?will go?up?is?certain.
That?she?is still?alive?is?a?consolation.
2.当谓语动词是seem,appear,be a pity.be a wonder,be likely等时，使用形式主语It，而将真正的主语放在句尾，这时从属连词that可省略：It appeared to scientists on earth (that) the stars had moved.
还有一些例如：绝大部分主语从句都借助先行主语放到句子后部去.
a.It?+be?+?形容词+that从句：
It is?natural?that?they?should?have?different?views.
It was?quite?obvious?that?she?didn’t?want?to?come.
b.It?+be?+?名词?+that?从句：
It’s a?shame?that?you’re?sick.
It’s?a?pity?that?he?can’t?swim.
c.It?+?动词（+?宾语或状语）+?that?从句：
It happened?that?she?wasn’t?in?that?day.
It seems?that?you’re?right.
d.It?+?动词的被动语态?+?that?从句：
It’s said?that?there?has?been?an?earthquake?in?India.
It’s reported?that?the?enemy?troops?have?crossed?the?border.
