Why does 哪 sometimes mean how?
哪 is a question word in Chinese that means "which" or "how".
哪 meaning "which" is something you'll often run into. For instance, you'll hear 哪 used when you're being asked to pick something or to identify something, as in the following question:
When used to mean "which", 哪 is usually followed by a measure word + a noun.
But, when you look at the different meanings of 哪, its other meaning is more puzzling: "how".
How does 哪 mean how?
"How" is an idiomatic meaning of 哪 , which is mainly used in this expression: 我 哪 知道？ How should I know? / How would I know?
我 哪 知道 is usually something you'll say when someone asks you a question that you really don't know how to answer or that you simply don't want to answer. Generally speaking, this expression is regarded as a defensive or defiant way to say "I don't know"; "I have no idea".
See how 哪 means "how" in context
These two example dialogues should make the use of 哪 as "how" and the use of 我 哪 知道 clearer:
哪 in a dialogue at work
A: 你 知道 他 上周 发生 什么 事 了 吗 ？
Nǐ zhīdào tā shàng zhōu fāshēng shénme shìle ma?
Do you know what happened to him last week?
B: 我 上周 不在 办公室, 我哪知道 ？
Wǒ shàng zhōu bùzài bàngōngshì, wǒ nǎ zhīdào?
How should/would I know since I wasn't in the office last week ?
哪 in a dialogue at school
A: 这 道 数学 题 的 答案 是 什么 ？
Zhè dào shùxué tí de dá'àn shì shénme? What is the answer to this math exercise?
B: 我哪知道 ？我 对 数学 一窍不通。
Wǒnǎzhīdào? Wǒ duì shùxué yīqiàobùtōng.
How should/would I know? I know nothing about math.
Note: 一窍不通 (yī qiào bù tōng): is a Chinese idiom which means "to know nothing about", "to lack the slightest knowledge of".
So? Is everything clearer now? Do you understand how 哪 sometimes mean how? We hope you do!
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