有关英语文法的问题

你用中文问, 我便用中文答, 方便你理解

MUST 是 modal verb (形态动词), 动词其中一种类, 另外一类是 main verb (主要动词)

其他的 modal verbs 包括有
can, could, may, might, will, would, shall, should, ought to, used to, need, had better, dare

Must 最普遍的结构:
Must + main verb (in base form),
例如. must go

不是 must + goes (went, gone, going)
不是 must to go, must后面不能有 to
verb in base form (或称 bare infinitive) 是动词最简单那个

其次的结构:
Must + be + past participle (過去分詞), e.g. must be done (~ in passive voice)

Must + be + present participle (现在分詞, verb-ing),
e.g. You must be getting tired.
You must be exaggerating. (exaggerate = 誇大)

Must + be + adjective (形容詞),
e.g. She must be tired.

Must + be + noun/pronoun (名詞/代名詞),
e.g. You must be Mary’s husband.
It must be him.

must可表达现在, 将来, 后跟现在完成式表过去 ( must have gone)

以下是其用法
1. 用在义务, 责任, 可用肯定句, 疑问句
Children must form a good habit.
Must I drink this nasty soup?

2. must not 表否定形式表不许, 不准
You must not eat in the library.
Cars must not park in front of the entrance.

3. must 可表坚定建议
You must come and see us sometime.
It must be protected at all costs.

4. must 可表推测
He must be tired after all that walking.
I can’t find my wallet. I must have left at home. (must + have + p.p.)

5. must 可表需要 (necessity)
The house must be clean if there are guests.

I must leave now. (现在)
I must leave by 6. (将来)
I had to leave by 6 yesterday. (过去)
过去式用 had to

记住 下列的文法規則 (grammar rules) 很重要:
Must 后面使用 have, 不是用 has
She must have a car. (比較 She has a car.)
Must 后面不能有 to

2015-02-17 10:06:24 補充：
must 還可以作 noun, 絕對必要的事物

If you live in the countryside, a car is a must.

2015-02-18 01:42:17 補充：
I must go now. (Present simple)
I must not go. (negative)
Must I go now? (question)
He must have left early. (Perfect)
He must be working late. (Progessive 進行式)

Must 不會轉 form. (無 past tense 與 past participle)
不會加 -s or -ed.

2015-02-18 02:30:19 補充：
The following six sentences are wrong.

1. You must not netting the fish until money have been paid.
"netting" is present participle, ~ No such tense!

2. You simply must read and learnt. (learnt ~ past tense)

3. You must go to the High Sheriff and paid the fine (paid ~ past tense)

2015-02-18 02:43:34 補充：
4. You are surprised it cost so much in your life-time !
cost ~ past tense; it ~ 3rd person singular

5. The Pool is one of the world's must-see aquarium
應用 aquariums ~ plural

6. Your pool must have been built years ago ! ~ wrong tense
years ago 不用 Present perfect

Grammar Point:-
must/have (got)to
Necessary and Obligation:-
Must and have (got) to are used in the present to say that something is necessary or should be done.;-
eg:-You must be home by 12 o'clock.
eg:-I must wash my car.and pool.
----
Must is used to talk about what the speaker or listener wants:-
eg:-I must finish cleaning the pool today.
-----
There is no past or future forms of must;use had to and has had to:-
eg:-I had to get rid of the dead carp
eg:-I have had to keep the pool clean.
-----
Will have to is used to talk about the future,
eg:-I'll have to buy the new fishes I need.
eg:-I have to go to the Aquarium tomorrow !
eg:-I have to go to the aquarium to see water creatures.
eg:-I have to go to the aquarium to see plants.
----
Must not is used to tell somebody not to do something
eg:-You must not netting the fish until money have been paid.
eg:-You must not leave the tap open to kill the fish !
----
Certainty:-
Both must and have to are used to say that you are certain about something:-
eg:-This must be the most dangerous carp in the pool.
About the past:-please use must have:-
eg:-Your pool must have been built years ago !
---------
"must" is a modal verb used to say that something is necessary or important:-
eg:-All visitors must report to reception center.
eg:-Cars must not park in front of the gate,Or a fine of $500.00 .
eg:-I must ask you not to do that again !
eg;-You must not say things like that if you're wrong !
eg:-You must go to the High Sheriff and paid the fine
eg:-You must admit =You should admit.You are surprised it cost so much in your life-time !
eg:-Must you always question everything I say?It is annoying..You must pay today !
------
Used to say that something is likely or logical:-
eg;-You must be hungry after all that fine .
You must have known what the law wants.
You must have learnt.
You simply must read and learnt.
The new book is a must for all lovers of fish !
We must get together soon for a fish-lunch !
The Pool is one of the world's must-see aquarium