Usages of bēi
你 要 一 杯 水 吗？nǐ yào yì bēi shuǐ ma?
Do you want a cup of water?
我 不 要 水，我 要 一 杯 茶。wǒ bú yào shuǐ,wǒ yào yì bēi chá.
I don’t want water; I want a cup of tea.
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