be

中文： 是、岁、在、正在

1. Used with past participles of verbs to form the passive voice. · The dog was saved by the boy.
2. Used with present participles of verbs to form the continuous aspect. · The woman is walking.· I shall be writing to you soon.
3. Used with to-infinitives of verbs to express intent, obligation, appropriateness, or relative future occurrence. · I am to leave tomorrow.· They are to stay here until I return.
4. Used with past participles of certain intransitive verbs to form the perfect aspect. · He is finished.· He is gone.
5. To exist. · There is just one woman in town who can help us.· (or, dialectally:) It is just one woman in town who can help us.
6. Used to declare the subject and object identical or equivalent. · Hi, I’m Jim.· 3 times 5 is fifteen.
7. Used to indicate that a predicate nominal applies to the subject. · Rex is a dog.· A dog is an animal.
8. Used to indicate that the subject has the qualities described by an adjective or prepositional phrase. · The sky is blue.

复数 are · He/she/it is · 过去式 was · 过去分词 been · -ing形式 being