Dare and need

The two verbs dare and need have characteristics of both modal verbs and main verbs. Because of this, they are called semi-modals. They sometimes behave like modal verbs and do not add -s to the form that goes with he, she, and it. That is, they have no 3rd person singular inflection. They are then followed by the base form of a main verb.

Need I say more?
Dare I ask how the project’s going?

The past form needed is not used as a modal; dared is occasionally used as a modal.The modal uses of these verbs are all negatives or questions.

Where will you all be today? – Need you ask?
You needn’t come if you’re busy.
Dare I suggest that we have a rota system?
I daren’t tell him the truth; he’ll go crazy.

Questions that are formed with need and dare are often set expressions such as Need I/you ask?, Dare I suggest…? and Need I/we say more?Dare and need sometimes behave like main verbs with -s inflection. In this case they are followed by the to infinitive. They can also use the auxiliary do and have the whole range of tenses appropriate to a main verb.

Louisa doesn’t need to know.
Does Paul need to go now?
Paul needs to go.
Dare to be different!
I don’t dare to mention it to him.

When dare or need are used as modal verbs in a positive statement, there must be a word of negative meaning in the same clause. This word can be outside the verb phrase and may be a word with a negative sense, such as only, never, hardly.

He need only ask and I will tell him.
No sensible driver dare risk that chance.

As a modal verb, dare has forms as follows:

I dare not go.	I dared not go.
He dare not go.	He dared not go.

Dare I do it?
Dare he do it?
Daren’t he do it?

As a main verb, dare has forms as follows:

I dare to do it.	I do not dare to do it.
He dares to do it.	He did not dare to do it.
He does not dare to do it.	Does he dare to do it?
He doesn’t dare to do it.	Doesn’t he dare to do it?

As a modal verb, need has forms as follows:

I need not go.	Need I go?
He need not go.	Need he go?
He needn’t go.	Needn’t he go?

As a main verb, need has forms as follows:

I need it.	I need to do it.
He needs it.	He needs to do it.
I do not need to go.	I do not need to do it.
He does not need to go.	Does he need to go?

Either of the two forms of dare and need can be used for sentences that have much the same meaning.

Anna didn’t dare to jump off the high fence.
Anna dared not jump off the high fence.
You don’t need to come if you don’t want to.
You needn’t come if you don’t want to.