Can and Could

'Can' expresses present ability, general possibility, or permission in informal contexts. 'Could' expresses past ability, polite requests, theoretical possibility, or suggestions. 'Could have + PP' describes an unrealised past ability or missed opportunity.

Formula

Can — present ability

S + can + V₁ (She can speak three languages.)

Can — permission

You can use the conference room this afternoon.

Could — past ability

S + could + V₁ (When she was an intern, she could speak only basic English.)

Could — polite request

Could you send me the updated figures?

Could have — unrealised

S + could have + PP (She could have handled it better.)

Cannot — prohibition

Employees cannot access this area without authorisation.

Example Sentences

Can I leave early today? I have a doctor's appointment.

When she joined the company, she could speak only basic English.

Could you review the proposal before tomorrow's meeting?

The system can process up to 10,000 transactions per minute.

She could have met the deadline if she had started earlier.

Employees cannot use personal devices in the server room.

With the new software, the team can now work remotely.

Could you please forward the client's contact details?

He could not access the database due to a network error.

Can the new hire manage the accounts independently?

Common Mistakes

Employees can to use the gym free of charge.

Employees can use the gym free of charge.

After a modal verb, always use the base verb WITHOUT 'to'.

She can spoke French before she moved abroad.

She could speak French before she moved abroad.

Use 'could' — not 'can' in past tense — for past ability.

Luyện tập ngay

2 bài tập tương tác: flashcard, điền từ, sắp xếp câu và tìm lỗi sai.

Đăng nhập để luyện tập