主語從句

    用作主語的從句叫主語從句。

    （That the earth goes around the sun） is known to all. （How this
happened） is not clear to anyone.（Whoever comes ） is welcome.（When
we shall have our sports meeting） is still a question. （Whether he will
come today） is still unknown.

    注意：

    1.主語從句是特殊疑問句，應該用特殊疑問詞加陳述句語序。

    2. that 引導的主語從句放在句首，不可省略that.

    3.主語從句常用it作形式主語，真正的主語放在后面，這時that可省略。

    It's a pity （that） you missed such a good opportunity. It's still
a question when we shall buy the new equipment. It's still unknown whether
he will come or not.

    4. It is + P.P.+ that ； It + Vi + that ，It作形式主語。

    It is said that the president will visit our company. It seems that
he has caught a cold.