Grammar connections
Unit 1 Present simple: I/you/we/they + base verb; he/she/it + verb-s/es. Negatives use do not/does not + base verb; questions begin Do/Does. Use it for habits, facts and timetables: “Mai makes models on Sundays.” After enjoy, use the -ing form: enjoy making models. A time expression such as every weekend signals a repeated habit, not an action only happening now.
Unit 2 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.
Unit 3 Past simple describes finished events at a past time. Regular verbs add -ed, with spelling changes such as study→studied. Common irregular forms include go→went, give→gave and make→made. Negative: did not + base verb; question: Did + subject + base verb? “They did not collected” is wrong: did already carries past time. Was/were form negatives and questions without did.