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 QKHT

(+) S + had + V3/ed 

(-) S + had + not + V3/ed 

(?) Had + S+ V3/ed?

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, ...

Công thức thì QKTD 

(+) S + was/were + Ving 

(-) S + was/were+ not + Ving 

(?) Was/Were +S +Ving? 

Công thức thì TLG

(+) S  +am/is/are + going to + V1 

(-) S  +am/is/are + not + going to + V1 

(?) Am/Is/Are + S + going to + V1? 

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

1. visited

DHNB: last weekend (QKD)

2. have been 

DHNB: for years (HTHT)

3. haven't left / went 

HTHT  + since  + QKD

4. haven't seen 

DHNB: before (HTHT)

5. am going to see 

DHNB: as planned (như dự định --> TLG)

6. was running 

QKD + when + QKTD

7. were walking / began

QKTD + when + QKD 

8. have studied 

DHNB: for 7 years now (HTHT)

9. went / had finished 

QKD + after + QKHT

`color{orange}{~MiaMB~}`