Особенности спряжения глагола «to buy» в различных временах заключаются в следующем:

• Present Simple (простое настоящее) — I buy, you buy, he, she buys, we buy, they buy. 2
• Past Simple (простое прошедшее) — I bought, you bought, he, she bought, we bought, they bought. 2
• Future Simple (простое будущее) — I will buy, you will buy, he, she will buy, we will buy, they will buy. 2
• Present Continuous (настоящее длительное) — I am buying, you are buying, he, she is buying, we are buying, they are buying. 2
• Past Continuous (прошедшее длительное) — I was buying, you were buying, he, she was buying, we were buying, they were buying. 2
• Future Continuous (будущее длительное) — I will be buying, you will be buying, he, she will be buying, we will be buying, they will be buying. 2
• Present Perfect (настоящее совершенное) — I have bought, you have bought, he, she has bought, we have bought, they have bought. 2
• Past Perfect (прошедшее совершенное) — I had bought, you had bought, he, she had bought, we had bought, they had bought. 2
• Future Perfect (будущее совершенное) — I will have bought, you will have bought, he, she will have bought, we will have bought, they will have bought. 2

Глагол «buy» — неправильный. 3