Giải giúp em và giải thích vì sao lại chọn đáp án đó

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 HTĐ (V: tobe)

(+) S + am/is/are ..

(-) S + am/is/are + not .. 

(?) Am/Is/Are + S + ... ? 

I + am

S số ít, he, she, it + is

S số nhiều, you ,we, they + are

Công thức thì HTĐ (V: thường)

S số ít, he, she, it 

(+) S + Vs/es

(-) S+ doesn't + V1 

(?) Does +S +V1?

S số nhiều, I, you, we, they

(+) S + V1 

(-) S+ don't + V1 

(?) Do + S+ V1? 

DHNB: always, usually, sometimes, often, never, seldom,....

Công thức thì TLĐ

(+) S + will + V1 

(-) S + won't + V1 

(?) Will + S+ V1? 

DHNB: in the future, in + năm ở TL, in + time, next week, next year, ....

Công thức thì HTTD 

(+) S + am/is/are + Ving 

(-) S + am/is/are + not + Ving 

(?) Am/Is/Are +S +Ving? 

DHNB: now, right now, (!), at present, at the moment,.....

Công thức thì QKTD 

(+) S + was/were + Ving 

(-) S + was/were+ not + Ving 

(?) Was/Were +S +Ving? 

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. has

DHNB: every day (HTD)

2. aren't 

DHNB: now (HTTD)

3. was / didn't have

DHNB: yesterday (QKD)

4. aren't inviting

DHNB: tonight (HTTD)

5. won't see / see

TLD + until + HTD

6. were you doing / rang

QKTD + when + QKD

7. aren't / are working

DHNB: now (HTTD)

8. will you do 

DHNB: next summer vacation (TLD)

9. was/has had

Since + QKD, HTHT

10.. haven't known
DHNB: so far (HTHT)

11. will be having

DHNB: this time tomorrow (TLTD)

12. came / was talking

When + QKD, QKTD

13. was watching

DHNB: at 8 o'clock last evening (QKTD)

14. entered / were talking

15. stops

16. got / had arrived

By the time + QKD, QKHT

17. had left 

After + QKHT, QKD

18. have ever seen

DHNB: ever (HTHT)

19. were studying

DHNB: this time yesterday (QKTD)

20. has been teaching

DHNB: for 20 years now (HTHTTD)

S + has/have + been  +Ving

`color{orange}{~STMIN~}`