Last time we discussed “would,” “could” and “should,” we looked at the way these words are used in conditionals. Recall that conditional sentences have two clauses, and are written in an “if… then” format. “Would,” “could,” and “should” appear in the then-clause of conditional sentences, but these three words are also used in many other ways.
In my next few posts on this topic, we’ll look “would,” “could,” and “should” outside of conditional sentences. This post focuses on “could.” As you’ll see in the guide below, “could” is a word with many different important grammatical uses.
Real possibility: When you know something is possible, but don’t know for sure if it’s true, you can express this by using “could.”
It is very cold and cloudy today. I haven’t looked out the window, but it could be snowing outside right now.
My favorite football team has been doing very well. They could win their next game.
Advice or suggestions (that aren’t likely to be followed): Have you ever advised someone to do something, but you knew they probably wouldn’t do it? When you give a suggestion to someone who will probably ignore it, you can u se “could” to express your frustration.
I know you really want to just stay at home. But since it’s such a beautiful day, you could come outside with me.
You always do your homework at the last minute, but you could start doing your assignments as soon as you get them.
Gentle, polite expression of disbelief: Sometimes you think something isn’t true, but it might not be a dishonest lie. It may only be a mistake or misunderstanding. In that kind of situation, you can politely disagree with what you’ve been told, using “could.”
The job advertisement says the salary is 1,000,000 USD per month. It couldn’t pay that much.
I suppose it could pay that much, but that seems unlikely. Surely there is a mistake in the ad.
Expression of surprise and displeasure at something someone has done, or at a bad situation: Use “could” this way if you are really upset about something, and you want to complain about it. Sentences that use “could” in this way are formed like questions.
Could you be any more rude?
How could there be so many ants in my apartment?
Past tense of can:
Right now, I can’t run very fast. However, when I was younger, I could run very quickly.
Expressing a possible event that never happened (with the word “have”): Here, “could” is used to describe an event that was possible in the past, but did not happen. This use is a lot like the third conditional, except that the sentence won’t use an “if” clause.
I wasn’t busy that night, so I could have gone to the movies. However, I decided not to.
Expressing an event that didn’t happen because it was never possible (also with the word “have”): In this use of “could” you explain why it was not possible for something to happen in the past.
Last night, I was very busy, so I couldn’t have gone to the movies.
Julius Caesar couldn’t have watched television or used a computer.
Politely requesting something or politely asking for permission:
Could you get the flour from the top cupboard? I’m too short to reach it.
Could I borrow this book? I can return it tomorrow.