Learn how to use DO, DOES and DID correctly. Also see - MOST COMMON MISTAKES IN ENGLISH & HOW TO AVOID THEM:    • 50 MOST COMMON MISTAKES in English Gr...  

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Transcript:
Hello and welcome. In this lesson, I am going to
show you how to use ‘do’, ‘does’, and ‘did’
correctly. I’ll first teach you the basics and
then I’ll give you some usage tips that will help
you to avoid mistakes with these forms. As
always, there is a quiz at the end of the video.
So let’s begin. Before we talk about the uses of
‘do’, ‘does’ and ‘did’, you need to know the
basic grammar rule with these forms. The rule is:
in the present, if the subject is I / You / We /
They or any plural noun, then we use ‘do’. If the
subject is He / She / It or any singular noun,
then we use ‘does’. This is when we talk about
the present. If we’re talking only about the
past, then it’s very easy. For any subject, we
use ‘did’. Alright, let’s do a quick test: in the
present, what do we use with I / You / We / They
or a plural? We use ‘do’. And with He / She / It
or a singular noun? We use ‘does’. What about in
the past? For any subject, we use ‘did’. OK,
let’s now talk about the first use of these three
forms. This is in making negative sentences. To
understand this, let’s first take a positive
sentence: “I like ice cream.” What is the verb
here? It’s ‘like’ – this is called the main verb
because it has the main meaning in the sentence.
So let’s make this negative. In English, the rule
for making negative sentences is that we add
‘not’ to the helping verb in the sentence. But
wait – there’s only one verb here – ‘like’ which
is the main verb. There is no other helping verb.
So what do we do now? Well, we add the verb ‘do’
as a helping verb in the sentence. Then, we put
‘not’ next to it. “I do not like ice cream.” is
the negative sentence. In speech, we usually
shorten this to ‘don’t’ – “I don’t like ice
cream.” OK, what about this? “He plays hockey.”
Remember that for He / She / It in the present,
we use ‘does’. Since we already have an –s in
‘does’, we remove it from the main verb – we
don’t say ‘plays’, we say ‘play’ – “He does not
play hockey” or “He doesn’t play hockey.” So the
structure of a negative sentence in the present
simple tense is subject + ‘do not’ or ‘does not’
+ the main verb in its base form (remember: don’t
add ‘s’ to the main verb) and then the rest of
the sentence. OK, let’s do an exercise now. Here
are a few more sentences. I want you to make them
all negative. Stop the video, think about your
answers, then play the video again and check.
Alright, here are the answers: “You don’t sing
very well.”, “We don’t travel to South Korea
every year.”, “They don’t live in a big house.”,
“She doesn’t want a new washing machine.”, “That
piano doesn’t look old.” Good. Now, these
sentences are all in the present tense. Let’s
quickly talk about what happens when we have past
tense sentences. Do you remember the rule for the
past tense? That’s right, we use ‘did’ for all
subjects. So we just say ‘did not’ or ‘didn’t’
plus the main verb in its base form. So here are
the past tense negative sentences – I’ve made
some slight changes to make them sound natural.
If you want, stop the video and read them to make
sure you understand. So this is the first use of
‘do’, ‘does’ and ‘did’ – making negative
sentences. Let’s now move on to the second use
and this is in making questions. Here’s an
example: “I look good in this shirt.” Let’s make
this a question. Once again, the rule is that we
need an auxiliary (or helping) verb for this.
Since the sentence doesn’t have a helping verb,
we’re going to use ‘do’. In questions, we put the
helping verb right at the beginning of the
sentence. So, the structure for present simple
tense questions is Do or Does + the subject + the
main verb in its base form and then the rest of
the sentence. So “Do I look good in this shirt?”
is the correct form. In this sentence, the main
verb is ‘look’. Just a quick tip: when you write,
don’t forget to add the question mark at the end
of a question.