To buy in English is to "purchase." This word comes from the Latin root "pretium," which means "price."

Here are some examples:

I need to purchase some milk from the grocery store.

She loves to purchase designer clothes from high-end stores.

We decided to purchase a new car last week.

In Chinese, "购买" (gòumǎi) is the equivalent of the English "purchase." Here are some Chinese translations of the example sentences above:

我需要从杂货店购买一些牛奶。(Wǒ xūyào cóng záhuòdiàn gòumǎi yīxiē niúnǎi.)

她喜欢从高端商店购买名牌衣服。(Tā xǐhuan cóng gāoduān shāngdiàn gòumǎi míngpái yīfu.)

我们决定上周购买一辆新车。(Wǒmen juédìng shàng zhōu gòumǎi yī liàng xīnchē.)