十四、復合句——名詞性從句

一個句子起名詞的作用，在句中做主語、賓語/介詞賓語、表語、同位語，那么這個句子就是名詞性從句。

1.what/whatever的用法

考生應把握：what是關系代詞，它起著引導從句并在從句中擔當一個成分這兩個作用。如：

They lost their way in the forest, and what made matters worse was that night began to fall.

(what既引導主語從句又在從句中做主語)

Water will continue to be what it is today—next in importance to oxygen.

(what既引導表語從句又在從句中做表語)

2.whoever和whomever的區(qū)別

whoever和whomever相當于anyone who，用主格與賓格取決于其在從句中做主語還是做賓語。如：

They always give the vacant seats to whoever comes first. (whoever在從句中做主語)

3.有關同位語從句的問題

(1)引導詞通常為that, 但有時因名詞內(nèi)容的需要，也可由whether及連接副詞why, when, where, how引導。that不表示任何意義，其他詞表示時間、地點、原因等。如：

The problem, where I will have my college education, at home or abroad, remains untouched.

(2)同位語從句有時與先行詞隔開，注意識別。如：

Evidence came up that specific speech sounds are recognized by babies as young as 6 months old.

4.whether與if在引導名詞性從句時的區(qū)別

(1)主語從句只能用whether引導;

(2)whether一般多用于賓語從句的肯定式，而if引導的從句可以有否定式;

(3)whether or not可以連在一起用，而if or not則不能，or not只能放在句末;

(4)whether可以引導介詞賓語從句，if則不能;

(5)賓語從句提至謂語前面時，只能用whether引導;

(6)在question, ask后面一般只用whether，question的同位語從句也用whether引導;

(7)后接不定式時，只能用whether。

5.動詞believe, expect, fancy, imagine, suppose, think后的賓語從句如為否定式，一般將否定詞轉(zhuǎn)移到主句謂語上。