What is the difference between "doesn't", "don't" and "not to"?


I'm a new English learner, I've found that while expressing negative ideas, sometimes "don't" and "doesn't" are used; but at other times "not to" is used. For example:

Your question doesn't specify exactly.

Can I use the following?

Your question not to specify exactly.

I wonder whenever we should use either of them?

Can somebody explain this grammar?

Sasan K

Posted 2017-03-29T04:51:13.360

Reputation: 153

Could you please provide some examples of the sentences you find confusing? "Not to" and "do not" are used in different ways, and it's not clear to me why you would confuse them. – Andrew – 2017-03-29T04:55:59.430

@Sasan K, the answer that you have accepted makes some incorrect assertions. 1) that don't is only used for advising or suggesting. 2) That doesn't is only used for describing behaviour and habits. 3) That not to is only used about personal resolutions. The real explanations are much simpler: see my answer. – JavaLatte – 2017-03-29T20:45:48.813



First, write the sentence in the positive, and see whether the verb that you want to negate is the main verb in the sentence. Consider talk in these three sentences:

he talks a lot - talk is main verb
he really likes to talk - talk is not the main verb
he likes talking - talk is not the main verb

Main verbs

If you want to negate the main verb and there is already an auxiliary verb (be, have, will, should could, must) in front of it, you insert not between the auxiliary and main verbs.

I am not going to the party
I have not seen him today
I will not have time tomorrow
You must not tell anybody about this

If the verb that you want to negate is be, just add not after it.

Dinner is ready
Dinner is not ready

The main verbs need and dare are special cases: in the positive, it is followed by to, and in the negative to is replaced by not.

You need to come
You need not come

For all other main verbs that don't have an auxiliary verb, you add the auxiliary verb do and then negate the auxiliary verb. The auxiliary verb has two cases: does for third person singular (he/she/it) and do for everything else. When negated, this can be written out in full do not, does not, or contracted don't, doesn't.

I want to go to the party
I don't want to go to the party

non-main verbs

If the verb that you want to negate is not the main verb and it's preceded by to, it's an infinitive: you negate it by putting not before the to

I told him to come
I told him not to come

Likewise, if the verb you want to negate is not the main verb and it's got an '-ing' ending, then you negate it by putting not before the verb.

thinking can get you into trouble
not thinking can get you into trouble


Posted 2017-03-29T04:51:13.360

Reputation: 43 538

1You've made life a bit complicated there. The verb BE is always an auxiliary verb apart from in a few very special constructions. That's why you stick n't/not either on it or directly after it!! :-) – Araucaria - Not here any more. – 2017-03-29T15:50:54.590

@Araucaria, looking at ten randomly selected instances of is, only one of them was as an auxiliary verb. The remainder were followed by a noun or an adjective. I think that it's worth mentioning as a special case. – JavaLatte – 2017-03-29T15:58:49.717

It doesn't matter - is is still an auxiliary there. What's missing is not an auxiliary it's the main verb!!!!! – Araucaria - Not here any more. – 2017-03-29T16:05:09.827

@Araucaria: that's probably a more difficult concept to get across than the approach that I have taken... – JavaLatte – 2017-03-29T16:22:30.600

1I promise you it isn't - I can say that as a teacher. All you need to do is take out the "The main verb BE is special case..." bit and you're home free. The confusion starts when you say be is an auxiliary and then add a special exemption for BE for some reason. Anyone who treats BE as a main verb when it's followed by a noun or adjective phrase always needs another four or five confusing rules to add on. If you don't, you only need one! :) – Araucaria - Not here any more. – 2017-03-29T18:03:07.477


Maybe see this post for why: "Is 'helper verb' old school?". (The answer is, yes!)

– Araucaria - Not here any more. – 2017-03-29T18:04:05.347


Those have different uses, as it seems to me.


used as a contraction for do not
Example: Don't waste your time.
Notice this is used for advising or suggesting people not to do things


used as a contraction of does not
Example: He doesn't follow his teacher's instructions.
Note: This is for describing behaviour and habits.

not to

This is more used in varied contexts, as in "not to say", "not to be", and so on, probably only while commenting about personal resoultions.
Example: I promise not to procrastinate.
If you're getting confused between 'not to' and 'to not', see this link

Don't and doesn't serve the same purpose but the difference is that doesn't is only used after third person singulars.

So, from the context "Your question doesn't specify exactly" is a more appropriate sounding sentence segment.

The other variant seems wrong as "not to"; makes it more intentional to "have not specified exactly.", and that sounds a bit awkward.


Posted 2017-03-29T04:51:13.360

Reputation: 113

You said after some specific word we can use not to? like promise! – Sasan K – 2017-03-29T05:58:19.857

Yes, but not always. It's only used in some specific constructs, I've seen it being used with people or pronouns representing people. – SBM – 2017-03-29T06:05:34.367

The difference between don't and doesn't depends only on whether the subject of the sentence is third person (he/she/it). And whether or not to use do has nothing to do with personal resolutions: it's mainly to do with whether or not the verb you want to negate is the main verb in the sentence. – JavaLatte – 2017-03-29T12:30:46.010

Yes that's basic, wonder why I didn't add it. – SBM – 2017-03-29T15:28:43.563