Modal verbs: can

Chinese language has at least three main verbs to express possibility: 能 (néng), 可以 (kěyǐ) and 会 (huì), each of which has slightly different nuances, although they may sometimes seem synonymous.

能 (néng) expresses the physical possibility to do something, it means to be able (intended as an innate ability), to have the permission or consensus to do something (generally used in questions and negative sentences) and indicates the existence of a possibility.

你真的能吃辣的！
nǐ zhēn de néng chī là de
[you really ST can to-eat spicy ST]
You really can handle spicy (food).

这里不能吸烟。
zhèlǐ bùnéng xīyān
[here not can to-smoke]
Smoking is not allowed here.

今天我有事儿，不能来。
jīntiān wǒ yǒushì er, bùnéng lái
[today I to-have business, not can to-come]
Today I’m busy, I cannot come.

可以 (kěyǐ) expresses the permission or consensus to do something and indicates the existence of conditions to be able to do something. 可以 and 能 are often interchangeable.

老师，我可以去厕所吗？
lǎoshī, wǒ kěyǐ qù cèsuǒ ma
[teacher, I can to go toilet IN.P]
Teacher, may I go to the toilet?

如果你明天好一点，我们可以去看演唱会。
rúguǒ nǐ míngtiān hǎo yīdiǎn, wǒmen kěyǐ qù kàn yǎnchàng huì
[if you tomorrow good a-little, we can to-go to-see concert]
If you’ll feel a little better tomorrow, we can go to the concert.

会 (huì) indicates an acquired ability (for example, through studying). It is also used as a future indicator (FUT).

她会说中文。
tā huì shuō zhōngwén
[she can to-speak Chinese]
She can (is able to) speak Chinese.

她发烧了，明天不会来。
tā fāshāole, míngtiān bù huì lái
[she to-have-a-fever, tomorrow not FUT to-come]
She has a fever, she will not come tomorrow.

Cover background picture by Carol Jeng (unsplash.com)