Lesson 27: Ability with “có thể”, “biết”

To say "can" in Vietnamese, you must distinguish between knowing how to do something and being able to do it.

Skill-Based "biết"

Use biết when talking about a learned skill or knowledge. It means "to know" or "know how."

Tôi biết bơi.
"I know (how to) swim."

Anh ấy biết lái xe.
"He knows (how to) drive."

Circumstantial "có thể"

Use có thể for general possibility or physical capability in the moment.

Hôm nay tôi có thể về muộn.
"Today I can (might) return late."

Bạn có thể giúp tôi không?
"Can you help me?"

Achievement-Based "được"

Putting được at the end of a sentence emphasizes that the result is achievable or manageable.

Tôi làm được.
"I can do it (successfully)."

Bạn có ăn được cay không?
"Can you eat spicy (food)? (Are you able to handle it?)"

Knowledge vs. Capability

Notice the difference:

• Biết tiếng Việt: I know the language (skill).
• Nói được tiếng Việt: I can physically speak it (active capability).

Examples

Em không biết nấu ăn.
"I don't know how to cook."

Tôi có thể đi bộ 10km.
"I can walk 10km."

Note on nuance

If you ask someone "Do you know spicy food?" (biết ăn cay), it sounds strange—like asking if they've met the food. Instead, use ăn được (can eat/handle). Use biết only for things you have to learn, like swimming, languages, or driving.