2.當謂語動詞是seem,appear,be a pity.be a wonder,be likely等時，使用形式主語It，而將真正的主語放在句尾，這時從屬連詞that可省略：It appeared to scientists on earth (that) the stars had moved.
還有一些例如：絕大部分主語從句都藉助先行主語放到句子後部去.
a.It +be + 形容詞+that從句：
It is natural that they should have different views.
It was quite obvious that she didn’t want to come.
b.It +be + 名詞 +that 從句：
It’s a shame that you’re sick.
It’s a pity that he can’t swim.
c.It + 動詞（+ 賓語或狀語）+ that 從句：
It happened that she wasn’t in that day.
It seems that you’re right.
d.It + 動詞的被動語態 + that 從句：
It’s said that there has been an earthquake in India.
It’s reported that the enemy troops have crossed the border.
1.that在句中不做成分。當主語從句位於句首時，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.
這是用的最多的一種主語從句,但把這種主語從句放在句首是很少的,只是為了強調或謂語較長時才這樣安排.例如：
That prices will go up is certain.
That she is still alive is a consolation.
2.當謂語動詞是seem,appear,be a pity.be a wonder,be likely等時，使用形式主語It，而將真正的主語放在句尾，這時從屬連詞that可省略：It appeared to scientists on earth (that) the stars had moved.
還有一些例如：絕大部分主語從句都藉助先行主語放到句子後部去.
a.It +be + 形容詞+that從句：
It is natural that they should have different views.
It was quite obvious that she didn’t want to come.
b.It +be + 名詞 +that 從句：
It’s a shame that you’re sick.
It’s a pity that he can’t swim.
c.It + 動詞（+ 賓語或狀語）+ that 從句：
It happened that she wasn’t in that day.
It seems that you’re right.
d.It + 動詞的被動語態 + that 從句：
It’s said that there has been an earthquake in India.
It’s reported that the enemy troops have crossed the border.