"Bought" is the past tense of "buy."
The past tense of regular verbs in Engpsh is usually formed by adding "-ed" to the base form of the verb. Irregular verbs, such as "buy," have a unique form for their past tense, which does not follow this pattern.
Examples of "buy" in the past tense include:
I bought a new car last week. (我上周买了一辆新车)
She bought some apples at the market. (她在市场上买了一些苹果)
They bought tickets to the concert months ago. (他们几个月前买了演唱会门票)