Modals - can/could

In this lesson, you will learn how to use can and could to talk about:

• ability
• permission
• requests

Could is often more polite than can.

1. What Are Modal Verbs?

Modal verbs are special verbs that help us talk about:

• ability
• permission
• requests

Important rules:

• Modal verbs do not change (no -s for he / she / it)
• They are followed by the base verb
• They do not use do / does

✓ “She can swim.”
✘ “She cans swim.”

✓ “Can you help me?”
✘ “Do you can help me?”

2. CAN – Main Uses

2.1 Ability

Use can to talk about things you are able to do now.

Positive form

Subject + can + base verb

Examples:

• “I can swim.”
• “She can drive.”
• “They can speak English.”

Negative form

Subject + cannot / can't + base verb

Examples:

• “I can’t swim.”
• “She can’t drive.”
• “They can't speak English.”

Short answers for ability questions:

• Yes → “Yes, I can.”
• No → “No, I can’t.”

2.2 Asking for Permission (Informal)

Use can to ask for permission and also to give permission in everyday situations.

Question form

Can + subject + base verb?

Examples (asking):

• “Can I sit here?”
• “Can we use your phone?”

Examples (giving permission):

• “Yes, you can.”
• “Sure, you can.”

2.3 Requests (Informal)

Use can to ask someone to do something.

Question form

Can + subject (you) + base verb?

Examples:

• “Can you help me?”
• “Can you repeat that, please?”

Can I... ? = permission

Can you... ? = request

3. COULD – Main Uses

3.1 Ability in the Past

Use could to talk about general ability in the past. For example: “When I was five, I could swim.” We usually do not use could for one single successful action in the past.

General ability: “When I was five, I could swim.”

One successful action: “Yesterday, I managed to open the door.”

Positive form

Subject + could + base verb

Examples:

• “I could ride a bike when I was five.”
• “She could read very early.”

Negative form

Subject + could not / couldn't + base verb

Examples:

• “I couldn't ride a bike when I was five.”
• “She couldn't read.”

3.2 Polite Requests

Use could to be more polite than can.

Question form

Could + subject + base verb?

Examples:

• “Could you help me, please?”
• “Could you open the door?”

(More polite than “Can you…?”)

3.3 Asking for Permission Politely

Use could to politely ask for permission.

Question form

Could + subject + base verb?

Examples:

• “Could I leave early today?”
• “Could we sit here?”

We often use could to ask for permission, but we usually answer with can: “Could I leave early?” — “Yes, you can.”

4. CAN vs COULD

Use can when:

• talking about ability now
• being informal

Use could when:

• talking about ability in the past
• being polite

Examples:

• “I can swim.” (ability now)
• “I could swim when I was five.” (ability in the past)

5. Easy Way to Remember

• Can → ability now; common for permission and requests
• Could → past ability; more polite for requests and asking permission