Affirmative:
- Present Tense: You are buying vegetables from the market.
- Past Tense: You were buying vegetables from the market.
- Future Tense: You will be buying vegetables from the market.

Negative:
- Present Tense: You are not buying vegetables from the market.
- Past Tense: You were not buying vegetables from the market.
- Future Tense: You will not be buying vegetables from the market.

Interrogative:
- Present Tense: Are you buying vegetables from the market?
- Past Tense: Were you buying vegetables from the market?
- Future Tense: Will you be buying vegetables from the market?

Interrogative Negative:
- Present Tense: Aren't you buying vegetables from the market?
- Past Tense: Weren't you buying vegetables from the market?
- Future Tense: Won't you be buying vegetables from the market?
Explanation:
- The continuous tense is used to describe actions that are ongoing or in progress at a specific time.
- In the affirmative form, we simply state that the action is happening in the present, past, or future.
- In the negative form, we add "not" after the auxiliary verb to indicate that the action is not happening.
- In the interrogative form, we invert the subject and the auxiliary verb to form a question.
- In the interrogative negative form, we combine the rules for both interrogative and negative forms.