句子的主语有哪些（句子成分主语）

主语：

(1)由名词、代词(人称代词用主格)、动词不定式、动名词等充当,说明动作是“谁”发出的。

如：The painter painted a very nice picture. (画家画了一幅漂亮的画。)

They fought against SARS bravely. (他们勇敢地与非典搏斗。)

To see is to believe. (耳听为虚眼见为实).

Helping animals is to help people. (帮助动物就是帮助人类。)

(2)动词不定式或动名词做主语时可用it代替,而不定式或动名词移至表语或宾语之后。

如：It is very comfortable to have a Class A seat during the long journey.

(在长途旅行中能有个甲等座位简直太舒服了。)

Eating too much is bad for your health.(=It is bad for your health eating too much.)

(吃得太多对你的身体不利。)

(3)口语中常见主语或“主--系”省略：

(It is) nothing. ((那)没有什么。)

(It) doesn’t matter. ((那)没有关系。)

(I) thank you. ((我)谢谢你。)

(4)反意问句的附加问句,主语必须是代词：

The man looks worried, doesn’t he? (这个人看上去很着急不是吗？)

Tigers are dangerous animals, aren’t they? (老虎是危险的动物不是吗？)

(5)祈使句一般省略主语。加主语时往往用来指定某个人。

Keep the keyboards clean, children. (孩子们请保持键盘的清洁。) (省略了主语)

You go there and fetch me a glass of water. (你去给我弄一杯水来。)

(6)主语一般在句首,但在问句中会处于第二位和句尾；倒装句及there be句型主语在动词之后。

如：Computers are made in this factory. (计算机生产于这家工厂。)

Where are they? (他们在哪儿？)

Does the boy like staying home? (这个男孩喜欢呆在家里吗？)

(7)主语与谓语必须保持单、复数的一致, 而谓语与表语或宾语之间没有这一要求。

Neither Jim nor Rose has passed the exam. (Jim和Rose都没有通过考试。)

The Chinese people are a hardworking and brave people. (中华民族是一个勤劳勇敢的民族。)

(8)主语可以由从句充当,详见“主语从句”。