be是一個連系動詞,它有自己不同的形式
現(xiàn)在時：be 進行時：being 過去時：was/were 過去分詞：been
它的后面必須跟形容詞或名詞作表語,與之構成系表結構,充當句子的謂語.
i am a student主語：i 謂語：am a student（系表結構）
being是它的現(xiàn)在進行時態(tài),一般不單獨用,而是用于現(xiàn)在進行時的被動語態(tài).（being+動詞過去分詞）
the bike is being repaired.單車正在被修理中.
it is being finished by him這正在被他完成中.
been是它的過去分詞,也不一般單獨使用,而是用于現(xiàn)在完成時、過去完成時以及需要它的句子.
i have been here for a long time.我已經(jīng)到這里有一段時間了.
至于你的問題,這與你想表達的意思有關.
你的工作是什么?
what do you do? what is your job?
那么這里選用do和is有什么根據(jù)呢?
第一句里面,第二個do是指你做什么,也就是你的工作,就是一個實義動詞.按中文說,what you do已經(jīng)足夠了.可是英語里面就不行,必須跟一個助動詞,也就是do.
這里就有了一個結論：當句子中有動詞時,我們就用助動詞do或是does.如果沒有動詞時,我們就選用is或是are,也就是b“Be”除了原形的“be”之外,還有另外七種形式：am, is, are, been, being, was, were.
在句子中,“be”可以是主動詞(The Principal Verb)或助動詞(The Auxiliary Verb).
當主動詞時,“be”在性質上屬于接系動詞(The Linking Verb), 后面要有名詞、形容詞、地方副詞或短語作補足語(The Complement).例如：
1. The man is a science teacher.
2. Mary's new dresses are colourful.
3. I have been there before.
4. Mother is in the kitchen now.
這四個都是陳述句,可以變成疑問句,方法簡單,把主語和“be”或助動詞對換位置即可：
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?
當“be”要在祈使句中出現(xiàn)時,它必須借重助動詞“do”或“don't”之助,如：
9. Don't be silly!
10. Do be obedient!
11. Don't be a fool!
“Be”有兩種縮寫法,如下：
12. He's not./He isn't.
13. You're not./You aren't...
但“am + not”的縮寫法只有一個：
14. I'm not.
有人用“ain't”, 但這并不是標準英語.
談過了“be”作主動詞的功能,現(xiàn)在看看“be”作助動詞時,有些什么用法：
1.“Be + 現(xiàn)在分詞”以組成進行式時態(tài)(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 + 過去分詞”以組成被動語態(tài)(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.