It代替从句作
形式主语的常见句型
1. it 代替连词 that 引导的从句作形式主语。
1) it + be +
过去分词 + that 从句:
It's said that Tom has come back from abroad .
It was reported that dozens of children died in the accident .
可用于该句型的过去分词还有：known , thought , told , believed , hoped , announced ,expected , decided , suggested等，该句型常可以转换成含有
宾语从句的复合句或者含有
不定式作主补的
简单句。如：
It's said that Tom has come back from abroad .
→People say that Tom has come back from abroad . →He is said to have come back from abroad .
2) It + be + 名词词组 + that 从句:
It's a pity that he can't swim for his age .
It's a wonder that you could finish such a hard task in such a short time .
可用于该句型的名词词组还有：an honour , a good thing , a fact , a surprise , good news等。
3) It + be /seem + 形容词 + that 从句:
It is likely that they will beat us tonight .今晚很可能他们会赢我们。
It doesn't seem that she will give us a hand .她帮我们的可能性似乎不太大。
可用于此句型的开容词还有；wonderful , true , good , right , wrong , (un)important ,useless , surprising , clear , possible , unusual , lucky , certain 等。
4) It + seem / appear / happen + that 从句:
It seems that he enjoys pop songs very much .看来他非常喜欢
流行歌曲。
It appears that Tom might change his mind .看来汤姆会改变主意。
It happened that I went out that day .碰巧我那天外出了。
2. it 代替连接代词或连接副词引导的从句作形式主语。
1) It is known (not decided , not made clear , found out , discussed , being discussed , being considered , a question , uncertain等) + 连接代词或连接副词引导的从句。
It is still a question when we shall have our sports meet . 我们将什么时候举行运动会还是一个问题。
It is uncertain whether he can attend this conference or not . 他能否来开会还不能确定。
2) It doesn't matter(doesn't matter too much , doesn't make too much difference等) + 连接代词或连接副词引导的从句。如：
It doesn't matter whether we go together or separately . 我们一起去还是分开去都可以。
It doesn't matter too much to me what you do or where you go . 你做什么或去什么地方，对我都无关紧要