Hello there. You know, I get this question all the time
– both from my students in my classes and on YouTube – what is the difference between
‘can’ and ‘could’? Well, in this lesson, I will teach you the
three main differences between these modal verbs and I’ll show you how to use them
correctly without making mistakes. As always, there is a quiz at the end of the
video to test your understanding. The very first thing you should know is the
basic use of ‘can’. This verb is used to show ability. Here are some examples: I can play the guitar. He can lift heavy weights. She can beat anyone at chess! So, all of these express ability. What about what ‘could’ then? Well, ‘could’ is just the past tense of
can. I can say: I could play the guitar when I
was in school. That means, I had the ability in the past,
but now I can’t play the guitar because it’s been a long time and I’m out of practice. Here a couple more examples: He could lift
heavy weights until he had the accident. She could beat anyone at chess in her prime! ‘In her prime’ means in her best years. Maybe when she was younger and was playing
competitively. So in these sentences – ‘can’ shows
present ability, and ‘could’ shows past ability. This is the first difference between the two
words. The second difference is when we want to talk
about possibility. To talk about what is possible, we normally
use ‘could’ and not ‘can’. Now, imagine that you and me, we’re both
waiting for a train at a train station. It’s time for the train to arrive but we
don’t see it. So I might say: Hmm, the train could be late. So I’m making a guess about the current
(or the present) situation, saying what is possible. Here’s another one: If you don’t study,
you could fail the exam. Are you sure to fail the exam? No. You could pass. But I’m saying that it’s possible that
if you don’t study, you’ll fail. Notice that this sentence talks about future
possibility. Ah, but I have a question – we just talked
about present and future possibility. Can we talk about past possibility? Yes, we can. Here’s an example: Robert could have gotten
the job if he had gone to the interview. So what do we understand from that? Well, there was a job interview. It was possible for Robert to go to the interview
and get the job. But he didn’t go. So he didn’t get the job. Now, as I said before, we use ‘could’
in all these sentences to talk about what’s possible in the past, present, and future,
but there is one situation where you can use ‘can’ and that is when you want to talk
about general possibility. For example: You can catch a cold if you go
out in the rain. Traveling across Europe can be quite expensive. You can see that these are just general statements
about what is possible in the world. In this case, it’s OK to use ‘can’,
but this use is less common. Normally, when we talk about possibility in
our lives we use ‘could’. Remember that. Alright, let’s now move on to the final
use of ‘can’ and ‘could’, and this is in polite expressions when we talk to people. There are four situations you need to know
about. The first is making suggestions. For this purpose, we use ‘could’. Here are some examples: We could try that
new Italian restaurant tonight. You could ask your sister to lend you some
money. In the first sentence, I’m making a suggestion
about where we can have dinner. In the second, I’m suggesting that if you
need money, why don’t you ask your sister? Using ‘could’ just makes it very polite. The second situation is making requests. Here, both ‘can’ and ‘could’ are possible:
Can you pass me the salt? Could you pass me the salt, please? Or on the phone: Can I speak to Rahul? Could I speak to Rahul, please? Did you notice that I said ‘please’ at
the end of the sentences with ‘could’? That’s because ‘could’ is more polite
than ‘can’. So if you are in a formal situation, like
if you’re talking to your boss or other superior and you want to be very polite, use
‘could’. If you’re with friends or family, then ‘can’
is fine. Our next function is making offers: Can I
get you something to drink? Could I get you something to drink, sir? Can I help you with that? Could I help you with that, madam? Again, notice the extra politeness with ‘could’. Finally, the last conversational situation
is when we want to ask for permission. Here are some sentences: Can I borrow your
pen? Could I borrow your pen, please? Can I take the day off tomorrow? Could I take the day off tomorrow? If you’re very friendly with your boss at
work, you would use ‘can’, but if your boss is very strict, then you would use ‘could’. OK, if you’re ready, it’s now time for
the quiz to see if you can use ‘can’ and ‘could’ correctly. On the screen, there are eight sentences. In each one, I want you to fill in the gap
with ‘can’ or ‘could’. Stop the video, think about your answers,
then play the video again and check. OK, here are the answers. How many did you get right? Let me know in the comments section below. If you have any questions about these, you
can ask me in the comments as well. If you liked this lesson, give it a thumbs
up by hitting the like button. If you’re new to my channel, make sure to
subscribe by clicking the subscribe button to get my latest lessons right here on YouTube. Happy learning and I will see you in another
lesson soon.
