Retrieve and diagnose
Simple sentences contain one main clause. They may have a subject + verb (“We exercise”), a subject + verb + object (“Mai drinks water”), or a subject + be + adjective (“She is active”). A subject or object can contain several words. “Mai and Nam walk to school” is still a simple sentence: one shared verb phrase. Use clear imperatives for advice: “Wear a hat.” Do not join unrelated clauses with just a comma.