Công thức thì HTHT

(+) S + has/have + V3/ed 

(-) S + has/have + not + V3/ed 

(?) Has/Have + S+ V3/ed?

DHNB: before, since + mốc thời gian, for + khoảng thời gian, yet, already, just,....

Công thức thì QKĐ (V: to be)

(+) S + was/were + ... 

(-) S + was/were + not ... 

(?) Was/Were + S ... ? 

S số ít, I, he, she, it + was

S số nhiều, you, we ,they + were

Công thức thì QKĐ (V: thường)

(+) S + V2/ed 

(-) S + didn't + V1 

(?) Did + S+ V1?

DHNB: ago, last (year, month ...), yesterday, in + năm QK, …

------------------------------------------------------------

1. didn’t see

DHNB: last Monday (QKD)

2. have written 

DHNB: up to the present (HTHT)

3. have / seen

HTHT + since + QKD

4. lost / has looked 

DHNB: until now (HTHT)

5. have read

DHNB: several times before (HTHT)

6. has written

DHNB: since last year (HTHT)

7. has taught / graduated

HTHT + since + QKD

8. hasn’t smoked 

DHNB: for 5 years (HTHT)

9. have / been

`color{orange}{~LeAiFuRuiHuiBao~}`