Can vs. Could

Understanding Confusing Grammar - Lesson #6

Many people ask about the difference between "can" and "could". In this lesson, we will go over how "can" and "could" are different and how we use each of them.

1. It is important to know that "could" is the past tense of "can". So, when we want to express "can" in the past tense, then we need to use "could".

We use "can" to talk about abilities, talents, or skills in the present tense.
  • Birds can fly.
  • I can swim.
  • She can sing well.
  • They can't play soccer.
  • He can't run fast.
  • Can you play golf?
And, we also use "can" talk about possibilities in the present or future.
  • I can attend the meeting tomorrow.
  • She can't come to the party.
  • He can meet us at 9 o'clock.
  • Can you come to my party?
  • What time can you meet us?
We use "could" in the same two ways when we are talking about something in the past.
  • I could dance well when I was young.
  • He could run fast when he was young, but now he is old and he cannot run fast.
  • They could not come to the party.
  • He could meet me on Saturday, but I was busy on Saturday. So, we didn't meet.
Remember that we use present tense verbs with real conditionals.
  • If I don't work tomorrow, then I can help you.
  • If you want, you can come.
We use past tense verbs with unreal conditionals.
  • If she studied harder, she could get better scores.
  • If it weren't raining today, we could go on a hike.
2. We can use "could" in a different way. We can use "could" to make a polite request. We do this when we are asking for help or a favor. When "could" is used this way, it is the first word of a question.
  • Could you give me a ride to the airport?
  • Could you please help me with this project?
  • Could you open the door for me, please?
  • Could he lend us some money?
  • Could your boss give me a job?
We can also use "could" to ask for permission politely.
  • Could I borrow some money?
  • Could I use your phone for a second?
  • Could I go to the bathroom before we start the meeting?

First, it is important to remember that "can" is used to talk about the present or future, and "could" is used to talk about the past.
  • I can swim.
  • I couldn't swim when I was young.

  • I can't go now.
  • I can't go tomorrow.
  • I couldn't go yesterday.
It is also important to know that "could" can be used to make polite requests.
  • Could you teach me English?
  • Could you turn down the TV, please? It is too loud.
  • Could I borrow some money?
It is important to understand the difference between can and could if you want to speak English at a high level.