名詞性從句

[key]  b
[點撥] 賓語從句做介賓
2.that與 what
在名詞性從句中，that b 不充當句子成分，僅起連接作用，也無意義，而what可充當主語、賓語、表語等，起含義為“……的事（東西）”。
has it been decided that the artist will attend the meeting?
what the children looks forward to most was the new year’s coming?
例3
_____fashion differs from country to country may reflect the culture differences from one aspect.
a. what        b. that        c . this        d . which
[key]  b that
[點撥]不做成分，但引導的是主語從句，所以不能省略。
例4
_____caused the accident is still a complete mystery.
a. what        b. that        c . how        d. where
[key]  a 
[點撥] what在句子中做主語。
3.主語從句可用形式主語it 代替, 置于句首，而將真整的主語即主語從句放在后面。但what, whatever和whoever引導的主語從句不用it代替。
it is certain that she will be late.
例5
it is pretty well understand _____ controls the flow of carbon dioxide in and out the atmosphere today.
a. which        b. that        c. what        d. whether
[key] c
[點撥] it為形式主語，what 引導的句子做真正的主語。
例6
it worried her a bit _____ her hair was turning grey.
a. while        b. if        c. that        d. for
[key]  c
[點撥] it為形式主語，而真正的主語是有 that 引導的從句。
特別提醒：
1）主語從句的that在口語或非正式文體中如果不在句首可以省略，但that從句位于句首時決不能省略。
it’s a pity (that) you are leaving.
it is certain (that) she will do well in the english exam.
2）主語從句除了that外，還可以用where, whether, when, why等詞引導。
it doesn’t matter whether they will come or not.
it has not been yet decided who will speak at the meeting.
4. who與 whoever
whoever意思為“凡……者”相當于anyone who+定語從句。它既可作主句的主語，又可作從句的主語，強調人。而who引導主語從句，只在從句中作主語，強調事。
whoever is more or less advanced can pass the text.
i will give this dictionary to whoever win the games.
例7
_____leaves the room last ought to turn off the lights.
a. anyone        b. the person        c. whoever        d. whom