Công thức thì HTHT

(+) S + has/have + V3/ed 

(-) S + has/have + not + V3/ed 

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

Wh + has/have + S+  V3/ed?

S số ít, he, she, it + has

S số nhiều, you, I, we, they + have

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: 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, ...

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

III)

1. has worked

DHNB: for two years (HTHT)

2. seemed 

When + QKD, QKD

3. has improved

DHNB: since last month (HTHT)

4. haven't heard

DHNB: for nearly a year (HTHT)

5. went

IV)

1. had graduated 

DHNB: by the end of last summer (QKHT)

2. had already left

When + QKD, QKHT

3. had phoned

QKHT + after + QKD

4. did you visit

DHNB: last year (QKD)

5. hadn't finished 

QKHT + when + QKD

`color{orange}{~LeAiFuRuiHuiBao~}`