The semi-modal NEED
Present and future
Need can behave either as a modal verb or as a main verb:
As a modal verb, need is most typically used in negative sentences or in affirmative sentences with a negative meaning. It expresses absence of obligation or necessity, and it is followed by a bare infinitive: You needn't worry about that.
No one need be surprised at what happened.
You need only just ask.
I doubt whether I need help you.
Need as a modal verb also occurs in interrogative sentences, but this use is much more formaclass="underline" Need you make so much noise?
Need as a main verb is followed by a to-infinitive and expresses that something is necessary. It can be used in affirmative, negative and interrogative sentences: Do you have a minute? I need to talk to you about something.
I don't need to be told that I should lose weight.
Do you need to use the hairdryer?
If you want good results, you will need to work harder.
Past
The past tense of the main verb need to is needed to: I needed to have my hair cut.
Why did they need to change the lock?
The negative form didn't need + to-infinitive normally refers to actions which were unnecessary and were not performed:We didn't need to buy any milk. We had plenty at home. (we didn't have to buy any milk, and we didn't buy any)
Need as a modal does not have a past tense form. Needn't + perfect bare infinitive (have + past participle), however, is used for actions which were performed but were unnecessary: We needn't have bought any milk. We still have plenty at home. (we bought some milk, but it wasn't necessary)
Quotes:
Gossip needn't be false to be evil - there's a lot of truth that shouldn't be passed around. - Frank A. Clark
Related topics:
The semi-modal DARE
Modals to express obligation: SHOULD, OUGHT TO
Present and future
Should and ought to + infinitive express obligation and duty. Should is used when we offer a subjective opinion, while ought to has a more general and more objective meaning:
I think you
should leave
.
We
ought to protect
the environment.
Past
Should and ought to + perfect infinitive express that an action which was desirable was not performed:
You
should have consulted
a doctor.
You
ought to have told
me earlier. Why didn't you tell me?
Quotes:
Gossip needn't be false to be evil - there's a lot of truth that shouldn't be passed around. - Frank A. Clark
We should read to give our souls a chance to luxuriate. - Henry Miller
Every English poet should master the rules of grammar before he attempts to bend or break them. - Robert Graves
The modal SHALL to express obligation
Shall is used to express formal rules and regulations or commands in an archaic style:
Visitors
shall be
accompanied at all times by a security guard.
You
shall not kill
.
Modals to express offers: CAN, COULD, WILL, SHALL, MAY
Can, could, will, shall and may are used to express offers:
Can
I
help
you?
May
I
carry
your suitcase, Madam?
(only in first-person questions)
I
could give
you a lift.
Shall
I
copy
this document for you?
(only in first-person questions)
I
will make
you a coffee.
Modals to express permission / prohibition: CAN, COULD, MAY, MIGHT, BE ALLOWED TO, MUSTN'T, BE TO
Present and future
Can and may are used to give permission. May is more formal and less common in everyday contexts:
You
can borrow
my car if you want.
Children
may use
the pool with adult supervision.
The negative forms cannot/can't, mustn't and may not (more formal) are used to express prohibitions:
I'm sorry, but you
can't stay
here.
You
mustn't touch
that Ming vase.
Non-committee members
may not vote
on committee issues.