Need' as a modal

Need has only some of the characteristics of modal verbs [> 11.1] in

that it occurs in questions, Weed you go?, and negatives, You needn't

go [> 11.52-53]. In Yes/No questions, a negative answer is often

expected:

Need you leave so soon? (= surely not/I hope not)

Yes/No questions with Need? can be answered with must or needn't Need I type this letter again? ~ Yes, you must/No, you needn't

Need + have + past participle behaves in the same way: Weed you have told him about my plans? You needn't have told him about my plans

Yes/No questions with Need., have.?can be answered:

Yes, I had to (no choice) No, / needn't have (I had a choice)

Need as a modal verb also occurs in combination with negative-type

adverbs like hardly, never, seldom, rarely and scarcely to make what

are effectively negative statements:

She need never know what you have just told me

I need hardly tell you how badly I feel about her departure

All you need do is to take a taxi from the airport (i.e. you need to

do nothing except take a taxi)

Need can also occur in clauses with a negative main clause: / don't think you need leave yet.

Need as a modal is mostly used in the negative (/ needn't go [> 11.53]) to express lack of necessity. Otherwise we generally use the full verb need to (used like any regular verb):

/ need to/I needed to go to the dentist this morning.

I don't need to/I didn't need to go to the dentist

When will you next need to go to the dentist?

Why did you need to go to the dentist? 'etc.

11 Modal auxiliaries and related verbs

Advisability/necessity: the present and future

Should ought to, etc refer to present time (except in indirect speech [> 15.13n6]) With the addition of adverbials such as this afternoon tomorrow, etc, they refer to future time