Correct Use of COULD and WOULD | What's the Difference? | Modal Verbs in English Grammar

Many people are confused about the correct use of ‘could’ and ‘would’.

In this lesson, I will teach you how to use these two modal verbs without mistakes.

There is a quiz at the end of the video to test your understanding.

OK, there are three main differences between ‘could’ and ‘would’ that you need

to know.

So let’s start with the first one: This is in the use of the past tense.

‘Could’ is the past tense of ‘can’ and ‘would’ is the past tense of ‘will’.

Take this sentence: “I can run a mile in 10 minutes.”

This means I have this ability (to run a mile within 10 minutes).

This is in the present tense but we can change it to the past by saying “I could run a

mile in 10 minutes when I was younger.”

It means I had the ability in the past but I don’t have it now.

In this next example: “I know we will win the match.”

So maybe we’re on the same team, and I tell you “I know we will win.”

I’m confident.

But if the match happened in the past (it’s already finished), and I want to say that

I was confident, I can say “I knew we would win the match.”

Here, ‘will’ becomes ‘would’.

This is the first difference.

The second difference relates to talking about possible situations and imaginary situations.

Take this example: “It could rain tonight.”

So I look at the sky and I see clouds.

And I make a prediction about the future.

Here’s another sentence – “John isn’t answering his phone.

He could be busy.”

That is I’m saying that it’s possible that he’s busy.

Notice that in both of these sentences, ‘could’ is not a past tense form – it’s just used

to show possibility.

But I cannot use ‘would’ for this purpose.

So, these are possible situations, but when we talk about imaginary situations, we prefer

to use ‘would’.

For example, “If I had a million dollars, I would buy a beach house.”

Again, don’t be confused by the past tense.

We say “If I had” and “I would buy” because we want to show that this is imagination

– it’s not reality (I don’t have a million dollars).

Here’s another example: “If Shirley worked hard, she would get a promotion.”

This means she doesn’t work hard (she’s lazy), so she’s not going to get a promotion.

Now, in both of these sentences, we can use ‘could’ to show imaginary ability but

it’s less common.

‘Would’ is used a lot more when it comes to imaginary situations.

This is the second difference.

Let’s now move on to the third and final difference – and this is in polite expressions.

There are four functions that are important for us – making suggestions, offers, requests

and asking for permission.

First, to make suggestions, we normally use ‘could’ as in this example: “We could

try that new Italian restaurant.”

So imagine that we’re planning to have dinner together and I make this suggestion.

Here, using ‘would’ is wrong.

But to make an offer, we prefer ‘would’.

For example: “Would you like some tea?”

That means, I have tea and I’m asking you if you want some.

Here, we cannot use ‘could’.

But making requests is different because it is possible to use both ‘could’ and ‘would’.

For example, “Could you open the window, please?”

You can also say, “Would you open the window, please?”

although this is very formal and polite.

However, we also sometimes use “Would you mind…” as in “Would you mind opening

the window?”

This is a request, but this phrase is fixed – you cannot say “Could you mind…?”

And when we ask for permission, again there are expressions with both ‘could’ and

‘would’.

For example, “Could I borrow your car for a couple of days?”

Maybe I’m saying this to a friend, so I’m asking my friend for permission to use his

or her car.

I can also say, “Would it be OK if I borrowed your car for a couple of days?” or “Would

you mind if I borrowed your car for a couple of days?”

‘Would you mind’ can be used to ask permission as well.

Notice that when we use ‘would it be OK if’ or ‘would you mind if’, we use the

verb in the past tense – ‘borrowed’, but that’s just a grammar rule – we’re

still asking for permission for the future.

Alright, these are the differences between ‘could’ and ‘would’, and if you’re

ready, it’s now time for the test.

There are eight sentences on the screen.

In each one, I want you to choose the correct word – ‘could’ or ‘would’.

Stop the video, think about your answers, then play the video again and check.

Alright, here are the answers.

Let me know how many you got correct in the comments.

If you’re not sure about any of these, you can ask me in the comments as well.

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Happy learning and I will see you in another lesson soon.