第三人称就是他、她、它，he，she，it
be动词意思和用法很多，一般的意思是是，此种用法，有多种变化形式，is，am，are，was，were.另外，be动词还有成为的意思。
“Be”除了原形的“be”之外，还有另外七种形式：am, is, are, been, being, was, were.
例句对照
【当主动词时，“be”在性质上属于接系动词(The Linking Verb), 后面要有名词、形容词、地方副词或短语作补足语(The Complement)。例如：
1. The man is a science teacher.
这个男子是一位科学教师
2. Mary's new dresses are colourful.
玛丽的新衣服色彩鲜艳
3. I have been there before.
我以前去过那里
4. My mother is watching TV in the room.
母亲现在在客厅看电视 【这四个都是陈述句，可以变成疑问句，方法简单，把主语和“be”或助动词对换位置即可：
5. Is the man a science teacher?
6. Are Mary's new dresses colourful?
7. Have I been there before?
8. Is mother in the kitchen now?
【当“be”要在祈使句中出现时，它必须借重助动词“do”或“don't”之助，如：
9. Don't be silly!
10. Do be obedient!
11. Don't be a fool!
【“Be”有两种缩写法，如下：
12. He's not...../He isn't....
13. You're not...../You aren't...
【但“am + not”的缩写法只有一个：
14. I'm not.
有人用“ain't”, 但这并不是标准英语。
谈过了“be”作主动词的功能，现在看看“be”作助动词时，有些什么用法：
【1.】“Be + 现在分词”以组成进行式时态(Continuous Tenses)，如：
15. Tony's maid is washing his new car.
16. The children are playing in the field.
17. Samuel was eating when I came in.
18. We have been living here since 1959.
【2.】“Be + 过去分词”以组成被动语态(The Passive Voice),如：
19. Her money in the drawer was stolen.
20. A number of good jobs are taken up byforeigners.
21. David studied in Taiwan but has been trained as a language lecturer in America.
22. Can all the wonderful birds be found in our Bird Park?
23. The disobedient boy was told to stand out- side the classroom.
24. Steps are being taken to reduce traffic con- gestion during peak hours.
25. Dishonest students will be immediately dealt with.
追问还有没有类似这些的？
什么主语 ？ 什么型态动词？啊什么的。
追答25个句子还不够吗？如果是这样，建议你去买本英语语法书了。：）