句子成分之主語(yǔ)

主語(yǔ)
主語(yǔ)是一個(gè)句子所敘述的主體，一般位于句首,通常由名詞性的詞來(lái)充當(dāng)。可由1.名詞、2.代詞、3.數(shù)詞、4.名詞化的形容詞（如the rich）5.不定式、6.動(dòng)名詞、7.短語(yǔ)、8.從句等表示。

1.名詞作主語(yǔ)
During the 1990s, American country music has become more and more popular.

2.代詞作主語(yǔ)
We often speak English in class.

3.數(shù)詞作主語(yǔ)
One-third of the students in this class are girls.

4.不定式作主語(yǔ)
To swim in the river is a great pleasure.
It is necessary to master a foreign language.（it作形式主語(yǔ)，真正的主語(yǔ)為后面的不定式）

5.動(dòng)名詞作主語(yǔ)
Smoking does harm to the health.

6.名詞化的形容詞作主語(yǔ)
The rich should help the poor.

7.短語(yǔ)作主語(yǔ)
How to do well is an important question.
Early to bed and early to rise makes a man healthy.

8.從句作主語(yǔ)
When we are going to have an English test has not been decided.
That he isn’t at home is not true. (that不能省略)