DO vs DOES – the difference between DO and DOES

The difference between DO and DOES can be tricky, especially for beginners. The verb ‘to do’ is used in multiple ways in English and as such can be easily used wrong. Let’s have a look at specific examples of how to use it correctly and what the difference between DO and DOES is.

How and why to use DOES instead of DO

The third person singular usually adds the ‘-s’ ending to verbs. That’s how DO becomes DOES. But what about the extra ‘e’ in ‘-es’? Why is the third person singular DOES and not DOS? And what’s the difference between ‘-s’ and ‘-es’? Read on to find all the answers.

First of all, we need to say that in addition to the third person singular, the ‘-s’ ending is also used in other contexts, for example when making plural nouns. That means that the rules described below are general rules that don’t apply just to verbs but also to other words.

The simple ‘-s’ ending

As a rule of thumb, we add the ‘-s’ ending to the bare form of the word (= the infinitive of the verb, the singular noun etc.). This is true for almost all words except for those described in other sections.

An example of a verb in third person singular:

• I like music.
• He likes music.

An example of a plural noun:

• One mistake
•  More mistakes

Words ending in ‘-o, -s, -sh, -ch, -x’

However, if a word ends in ‘-o’, we add ‘-es’ rather than ‘-s’.

An example of a verb in third person singular:

• I do a lot of work.
• He does a lot of work.

An example of a plural noun:

• One potato
• More potatoes

While a lot of nouns end in ‘-o’, only very few verbs do. The most commonly used verbs ending in ‘-o’ are DO and GO.

The same rule is used for words ending in ‘-s’, ‘-sh’, ‘-ch’ or ‘-x’, which also take the ‘-es’ ending.

An example of a verb in third person singular:·       

• I watch TV.
• He watches TV.

An example of a plural noun:

• One sandwich
• More sandwiches

There are a number of other exceptions to the ‘-s’ ending rule, which we’re not going to discuss in detail, as our focus is on the verb DO.

Let’s finish by saying that this is a general rule and there’s no difference between the verb DO and other words in this aspect. The only difference between DO and DOES really is that DOES is used in the third person singular.

DO vs DOES as an auxiliary verb

The verb DO also has another specific role in English: it’s what’s called an auxiliary verb, which means it is used in combination with other main verbs to add grammatical meaning to a sentence. Typically, this would be to express a tense or a negative statement.

Other auxiliary verbs are HAVE, BE, WOULD and others.

DO NOT and DOES NOT – the verb DO in negative sentences

The verb DO (and DOES in third person singular) is also helpful if you want to make a sentence negative. Once again, DO and DOES are used as auxiliary verbs in negative statements.

The rule is quite simple. To make a sentence negative, add ‘not’ (or the contracted form ‘n’t’) to DO or DOES:

Examples of the full negative form:

• I do not like.
• You do not like.
• She does not like.
• We do not like.

Examples of the contracted negative form:

• I don’t like.
• You don’t like.
• She doesn’t like.
• We don’t like.

Other examples of how to use DON’T and DOESN’T in sentences:

• I drink coffee but I don’t drink tea.
• I don’t like my job.
• He likes football but he doesn’t like tennis.
• It doesn’t rain very often here.

Auxiliary verbs are always used with other main verbs and DO is no exception. The difference between DO and other verbs is that unlike other verbs, DO can be used in a single sentence twice: first as an auxiliary verb and then as a main verb.

Look at these examples:

• I don’t do it very often.
• John doesn’t do his job very well. (Can you see how DO vs DOES are used in the same sentence? DOESN’T is the auxiliary verb here, DO is the main verb.)

DO vs DOES – auxiliary verbs in questions

You can also use the verb DO (and DOES in third person singular) as an auxiliary verb in questions. In that case, you need to change the word order of the sentence and add DO/DOES before the pronoun.

Affirmative forms:

• I like
• You have
• She does
• We play

Questions:

• Do I like?
• Do you have?
• Does she do?
• Do we play?

And last but not least, the verb DO is also used in short answers to questions. The difference between these short answers and a simple Yes/No can seem unimportant to non-native speakers but there is a difference: Use these short answers if you want to sound more polite!

For example:

• Do you play tennis? – No, I don’t.
• Does John work hard? – Yes, he does.
• Does it often snow here? – No, it doesn’t.

How to use DO, DOES and DID to express emphasis

English students don’t often realize that the verb DO can also be used to emphasize the main verb.

That means that while this simple sentence is correct:

• I like music.

you can also add emphasis to the sentence using DO and say it like this:

• I do like music.

In this way, you can use DO, DOES and DID to emphasize other verbs in the present simple and past simple forms. However, you can’t do the same thing with other tenses because there is already another auxiliary verb used (for example HAS, WERE, AM etc.), which can’t be combined with DO or DOES.

Have a look at these examples:

• ‘I went to school yesterday,’ can be emphasized if you say ‘I did go to school yesterday.’
• ‘I noticed her,’ can be emphasized if you say ‘I did notice her.’

but

• ‘Did you go home?’ cannot be emphasized using DO because the question already uses DID.
• ‘Does he love you?’ cannot be emphasized using DO because the question already uses DOES.
• ‘He was watching TV at 10pm,’ cannot be emphasized using DO because the past continuous form already uses the auxiliary WAS.
• ‘She has taken the last piece,’ cannot be emphasized using DO because the present perfect form already uses the auxiliary HAS.

DO, DID, DONE – the past forms of the verb DO

It’s also worth mentioning that the verb DO is irregular, which means it takes different forms in the past and past participle. The difference between the conjugation of regular and irregular verbs is that irregular verbs don’t follow a regular pattern and you have to learn the past forms of irregular verbs by heart.

The good news is that while in the present the verb DO changes into DOES in the third person singular (a painful rule for a lot of English students!), the past and past participle forms of DO don’t change and the same form is used for all persons, as you can see in the chart below.

The forms of the irregular verb DO are:

InfinitivePast simplePast participleDO or DOESDIDDONE

Here are some examples of how to use DO in the past:

• I didn’t watch TV yesterday.
• Did you do the shopping?
• She didn’t see Jane last week.

Compound verbs with DO

The verb DO makes a number of other related verbs such as OVERDO, UNDO, REDO and others. All such verbs copy the irregular pattern of DO, so in fact, once you learn the conjugation of DO, you’ve learnt the conjugation of all its related verbs, too.

Let’s take the irregular verb OVERDO as an example. The other forms of OVERDO are:

• OVERDOES in third person singular
• OVERDID in the past simple
• OVERDONE in the past participle

Conclusion – the difference between DO and DOES

To put it (very) simply, the only difference in DO vs DOES is that DOES is used in the third person singular and DO in all the other persons.

However, DO can also be used as an auxiliary verb, which means there are some more rules to follow if it is used in questions and negative statements. Plus it’s also an irregular verb, taking the forms of DO, DID, DONE.

As you can see, things can get quite complicated with the verb DO, which is exactly the reason that makes it so particular and difficult to use for non-native speakers of English. But don’t worry, once you realize what the difference between DO and DOES is, using them will feel very natural.

Source: https://en.learniv.com/info/en/irregular-verbs/do-vs-does-the-difference-between-do-and-does/