主语从句有三类:
1. 由what等代词引导的主语从句: what表示“…所…的(东西)”, 在结构上等于一个名词加一个定语从句; whatever表示“所…的一切”; whoever表示“一切…的人”.
What you need is more practice
What is hard is to do good all one’s life and never do anything bad.
Whatever was said here must be kept secret.
Whatever I have is at your service.
Whoever comes will be welcome.
Whoever fails to see this will make a big blunder.
2. 由连词that引起的主语从句: 这类主语从句在大多数情况下都放到句子后部去, 而用代词it做形式上的主语:
That we need more equipment is quite obvious.
It is impossible that I may not able to come.
It doesn’t seem likely that she will be here.
在口语中连词that有时可以省略掉:
It’s good you’re so considerate.
It’s a pity you missed such a fine talk.
3. 由连接代词或连接副词(或whether)引起的主语从句: 这类主语从句, 也可以放到句子后部去, 前面用it做形式上的主语.
When we shall have our sports meet is still a question.
It is still a question when we shall have our sports meet.
Whether he will join us won’t make too much difference.
It won’t make too much difference whether he will join us.
