"What should I buy?" is a common question that people may ask when they are trying to decide on a purchase. It is a way of asking for advice or suggestions on what to buy.

The phrase "what should I buy?" is made up of the pronoun "I," the modal verb "should," and the verb "buy." "I" is the pronoun used to refer to the person speaking or writing, and "should" is a modal verb that is used to indicate a recommendation or obpgation. "Buy" is a verb that means to obtain something by paying money for it.

Here are some example sentences using the phrase "what should I buy?":

"I need a new laptop, but I'm not sure what to get. What should I buy?"
"I have some extra money and I'm thinking about buying a gift for my friend. What do you think I should buy?"
"I'm trying to save money, but I also want to treat myself to something nice. What should I buy?"

In Chinese, the phrase "what should I buy?" can be translated as "我应该买什么?" (wǒ yīnggāi mǎi shénme?). The pronoun "我" (wǒ) means "I," the modal verb "应该" (yīnggāi) means "should," and the verb "买" (mǎi) means "buy."