I- Special verbs
1. Auxiliary verbs (Helping verbs – Trợ động từ)
BE (is / are / am / was / were / been)
DO (does / did)
HAVE (has / had)
2. Modal (Defective) verbs (Động từ hình thái – Động từ khuyết thiếu)
CAN (COULD), MAY (MIGHT), SHALL (SHOULD), WILL (WOULD), MUST, NEED, DARE, USED (to), OUGHT (to)
Necessity (cần thiết): must, have (got) to, needn’t and mustn’t
Ex: I must go to school.
Obligation (bắt buộc) and advice (khuyên bảo): should, ought to
Ex: You should read this book.
Permission (xin phép) : can, could, may might and be allowed
Ex: You can walk on the grass here.
Certainty (sự chắc chắn): will, must and can’t
Ex: Nam must be Vietnamese.
Probability (có lẽ): should and ought
Ex: The rain should stop soon.
Possibility (có thể): may, might, can and could
Ex: The students may be in the library.
Ability (khả năng): can, could and be able to
Ex: Nam can swim in the river.
Unreal situations: (tình huống không thật) : would
Habits (thói quen): will, would and used to
Challenge (thách thức) : dare
3. Modal verbs in the past
Modals verbs + have + Past participle
Ex: You should have worked harder. (Lẽ ra bạn nên học chăm hơn)
Ex: Nam must have won the first lottery. (Hẳn Nam đã trúng sổ độc đắc)
4. Modal verbs
a) No ending -S: Ex: He speaks Chinese very well.
b) Not followed by TO: Ex: He wanted to go out last night.
Exc.: He ought to help his friends.
c) Interrogative form: Ex: Do you speak French well?
Ex: Have you been to Hanoi?
d) Negative form: Ex: He didn’t go shopping last week.
II – Ordinary verbs
1. Vordinary → (past & Past Participle) + ED
2. Vordinary in Negative & interrogative, we must use the auxiliary DO (DOES/DID) is.