英語的“be”是個特別動詞;有些語言，如中文和馬來文，并沒有“be”這樣的動詞。

“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，現在看看“be”作助動詞時，有些什么用法：

1.“Be + 現在分詞”以組成進行式時態(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(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.

從上面例子看，“be”這動詞外貌平凡，但內涵豐厚。如果沒有“be”，補足語的橋梁斷了。如果沒有“be”,何來進行式時態和被動語態?缺了這幾樣重要的句式，英語還像英語嗎?