四、语法详解

主语从句

主语从句有两种：

1.主语从句（ the subject clause）在句中作主语，有以下两种结构

（1）主语从句位于句首。

Who kept the door open all night was unknown.

谁让门整夜开着，没人知道。

(2)主语从句位于句尾，使用先行词 it 作形式主语。

It was right that the temple was rescued.

重修寺庙是正确的。

主语从句能用 it 作形式上的主语。常见 it 作形式主语的句型有：

①It +be +形容词（clear, true, natural, good, possible, likely, certain, wonderful, fancy, etc）+ that 从句。

It is certain that she will do well in her exam.

她肯定会考好。

②It + be+名词词组（no wonder, an honour, a pity, no surprise, a good thing, etc）+ that 从句。

It is a pity that we can't go.

真可惜我们不能去。

③It + be +过去分词（said, reported, thought, expected, decided, etc）+that 从句。

It is said that Mr. Green has arrived in Beijing.