This is one of the trickiest comparisons, as 会 (huì), 能 (néng),
and 可以 (kěyǐ) are often translated as "can." Sometimes they are
explained as: 会 means "know how to," 能 means "to be able to," and
可以 means "to have permission to." Actually, they overlap
somewhat.
Basic Meanings
The words 会 (huì), 能 (néng), and 可以 (kěyǐ) actually overlap a
little in meaning. The first step is to understand their basic
meanings, though:
会 (huì) can mean "know how to" and can express an action that
you had to learn or be trained in to do.
能 (néng) means "to be able to" and expresses having a certain
ability or having obtained a certain minimum requirement.
可以 (kěyǐ) means "may" or "to be allowed to" and expresses
having another person's permission.
As for overlap, this graphic helps explain nicely:
The regions marked by letters are explained in the sections
below:
A: ability in the sense of “know how to” (会 (huì) is more
common than 能 (néng))
B: permission/request (use 能 (néng) or 可以 (kěyǐ))
C: possibility (use 能 (néng) or 可以 (kěyǐ))
D: permission not granted (use 不可以 (bù kěyǐ))
E: impossibility (use 不能 (bù néng))
Expressing Ability
Both 会 and 能 can be used to express ability in something.
Structure
会/能 + Verb
Examples
我们 都 会 游泳 。Wǒmen dōu huì
yóuyǒng.We all can swim.
他 不 会 修 电脑 。Tā bù huì
xiū diànnǎo.He doesn't know how to fix
computers.
你 真的 能 吃 三 碗 米饭 吗 ?Nǐ zhēnde
néng chī sān wǎn mǐfàn ma?Are
you really able to eat three bowls of rice?
B: 不 好意思 ,我 只 能 说 一点 。B: Bù
hǎoyìsi, wǒ zhǐ néng shuō yīdiǎn.Sorry, I can only speak a little.
Expressing Permission
可以 is used to ask for or give permission. However, 能 can also be
used to replace 可以 interchangeably.
Note: When a question is asked using 能/可以 it
can be answered with 不能/不可以, meaning no, and only 可以 meaning yes.
Chinese don't really answer with just 能。
Structure
可以 / 能 + Verb
Examples
我 可以 走 了 吗 ?Wǒ kěyǐ zǒu
le ma?Am I allowed to leave
now?
你 能 不 能 帮 我 一下 吗 ?Nǐ néng bu
néng bāng wǒ yīxià ma?Could you
help me a bit?
动物 不 能 进 。Dòngwù bù néng
jìn.Animals are not allowed to come
in.
明天 你 能 早点 来 吗 ?Míngtiān nǐ
néng zǎodiǎn lái ma?Is it
possible for you to come al little earlier tomorrow?
可 不 可以 换 一 个 ?Kě bù kěyǐ
huàn yī gè?Is it possible to change
it?
能 不 参加 吗 ?Néngbù cānjiā
ma?Is it possible to not
attend?
Example dialogue:
A: 能 不 能 取消 今天 的 课 ?A: Néng
bù néng qǔxiāo jīntiān de kè?Is it
possible to cancel today's lesson?
B: 不 能 。B: Bù
néng.Impossible.
Talking about the Future
Only 会 can be used to mean something is going to happen. It
expresses that something in the future will happen and is often
used to express trends or possibilities.
Structure
会 + Verb / Adj.
Examples
他 不 会 跟 你 结婚 。Tā bù huì
gēn nǐ jiéhūn.He's not going to marry
you.
你 会 生 我 的 气 吗 ?Nǐ huì
shēng wǒ de qì ma?Will you be mad at
me?
这样 穿 会 好看 吗 ?Zhèyàng chuān
huì hǎokàn ma?Will I look good
if I dress like this?
Example dialogue:
A: 今天 会 下雨 吗 ?Jīntiān
huì xiàyǔ ma?Is it going to
rain today?
B: 我看 不 会 。Wǒ kàn bù
huì.I don't think it
will.
Using Adverbs to Add
Emphasis
By placing 很 (hěn) before 会, it adds emphasis to the level of
ability and skill on the action presented. 很会 is commonly used to
mean 'to be good at" and expresses being very skillful at
something, or doing something very well. It can be translated as
"really can," as in "you really can speak Chinese!," in
other words, "you are good at speaking Chinese."
When 很 is placed in front of 能, the meaning takes on a
amazed/surprised tone on the action. Although more rarely used, it
emphasis quantity and amount. 很能 is most commonly used with 吃(chī)
to eat, and 睡 (shuì) to sleep. It's like the English equivalent of
saying you "can really" do something. For example saying that
someone "can really sleep" means that they can sleep a
lot.
Note: 很可以 is not a phrase and therefore can not
be used with 会 to add emphasis. Other adverbs like 真 (zhēn), 太
(tài), 这么 (zhème) etc. can also be used.
Structure
很 + 会/能 + Verb
Examples
这个 女生 很会 打扮 。Zhège nǚshēng hěnhuì
dǎban.This girl knows how to dress up
really well.
我 妈妈 很会 做饭 。My
mom cooks very well.Wǒ māma
hěnhuì zuòfàn.My mother really knows how to cook.
他 很会 说话 。The
subject has good speaking skills.Tā
hěnhuì shuōhuà.He's a smooth talker.
他 很能 说 。Tā
hěnnéng shuō.He's quite a talker.
Note that 很可以说 is wrong and it doesn't mean anything.
Examples used with other adverbs:
他 太能 睡 了 。The
subject can sleep a lot, for many hours.Tā tàinéng shuì
le.He can really sleep.
没想到 你 这么能 吃苦 。Méixiǎngdào nǐ zhèmenéng
chīkǔ.I didn't expect you to be a person
who can handle so many burdens.
你 真能 吃 !The
subject can eat a lot.Nǐ
zhēnnéng chī!Wow, you really can eat!
中国 人 真会 吃 !The
subject has great knowledge about food and its culture, a true
connoisseur.Zhōngguó rén
zhēnhuì chī!Chinese people really can eat.
Note that 很可以吃 is wrong and it doesn't mean anything.
Similar
expression with different meanings
我 的 脚 好 了 ,现在 又 能 跳舞 了 。Wǒ de
jiǎo hǎo le, xiànzài yòu néng tiàowǔ
le.I am able to dance now since my foot
is better. (The condition changed)
我 学 了 两 个 月 ,现在 我 会 跳舞 了 。Wǒ xué
le liǎng gè yuè, xiànzài wǒ huì tiàowǔ
le.I studied for two months. I know how
to dance now. (It's a learned skill)
我 爸妈 同意 了 ,现在 我 可以 跳舞 了 。Wǒ fùmǔ
tóngyì le, xiànzài wǒ kěyǐ tiàowǔ le.My parents agreed. I'm allowed to dance now. (The dad gave
permission)
Note that none of the three can be followed by the aspectual
particle 过.