Emphatic adverb "ke"
可 can be used like 很 or 非常 to add emphasis to an adjective. It is stronger than other modifiers, as 可 relates to the speakers expectation of the situation. The exact way 可 is used is hard to grasp, as it is very reliant on context.
In these examples, 可 is used a bit like 很, as it is used to emphasize an adjective:
- 这 个 小 狗 可 淘气!(I never expected dogs to be this naughty)
- 哇,这 个 糖醋 鲤 鸡 可 好吃 啊!(This sweet and sour pork is just like I dreamed it would be)
So 可 can emphasize that what you are describing is the same as, or the opposite to your expectation.
In these examples 可 is used a bit like 真, and used to emphasize a verb:
- 你 可 来 了! At last! I never expected it would take so long for you to get here,
- 我 可 没 想 到 小 李 会 跟 他 女友 分手 I wouldn't in a million years think that they'd split up
- 你 可 别 喝 太 多 酒 (I'm expected you to drink a lot)
- 你 可 别 走 (I'm blocking your way, almost pleading with you not to leave, as I believe you have reason to leave)
In the last two sentences 可 is used with 别, and sounds a bit like "don't even think about..." in English
It can also be used to emphasize rhetorical questions:
- 这 件 事 他 可 知道? (I never thought he would know)
- 他 可 对 你 说 什么 呢? (What on earth he say to you, I can't imagine).
可 is generally used by Northern speakers, and is informal, only used in spoken Chinese.