Use passive constructions in the present indefinite tense.they buy vegetables in this shop

Present Indefinite.

They buy vegetables in this shop. (Active Voice).

Vegetables are bought in this shop by them. (Passive Voice).

Past Indefinite.

They bought vegetables in this shop. (Active Voice).

Vegetables were bought in this shop by them. (Passive Voice).

Future Indefinite.

They will buy vegetables in this shop. (Active Voice).

Vegetables will be bought in this shop by them. (Passive Voice).

Conditional.

They would buy vegetables in this shop. (Active Voice).

Vegetables would be bought in this shop by them. (Passive Voice).

Present Perfect.

They have bought vegetables in this shop. (Active Voice).

Vegetables have been bought in this shop by them. (Passive Voice).