Under state law, bar owners must buy their liquor from wholesalers.

依照州法律，酒吧经营者们必须从批发商们那儿购买酒。

《柯林斯英汉双解大词典》

If you must buy from the Internet, ensure that the website is that of a pharmacy you know and trust.

如果你必须从互联网上购买，要确保该网站是你所知道和信任的药店网站。

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I must buy some furniture.

我一定要买些家具。

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It said the government must buy two million dollars' worth of silver each month for that purpose.

VOA: special.2010.06.17

It is about two poor children who must buy milk for their sick mother.

VOA: special.2009.10.05

It said the government must buy four-and-one-half million ounces of silver each month.

VOA: special.2010.06.17

That would at least give the industry certainty about what it must buy and when.

ECONOMIST: Aviation

Electricity generators and some other industries must buy the permits to cover their carbon dioxide emissions.

WSJ: Vote Leaves EU Emissions Trading in Tatters

Electricity generators and others must buy the permits in order to emit carbon dioxide.

WSJ: Vote Leaves EU Emissions Trading in Tatters