`1.` He hasn't been abroad before.

He has never been abroad before.

`-` This is the first time S + have/has + Vpp

`=` S + have/has + never + Vpp  + before

`2.` We have learnt English for 5 years.

`-` S + started + V-ing + ... + time ago

`=` S + have/has + Vpp + for time

`3.` I haven't met her for 3 months.

The last time I met her was 3 months ago.

Three months have passed since I last met her.

`-` S + (last) + V-ed/c2 + ... + time ago

`=` S + haven't/hasn't + Vpp + for time

`4.` This is the first time I have tried this kind of cake.

`5.` We haven't met each other for a long time.

The last time we met each other was a long time ago.

`-` It is + time + since + S + (last) + V-ed/c2

`=` S + haven't/hasn't + Vpp + ... + for time

`6.` How long have you bought it ?

`-` When + did + S + V-inf + ... ?

`=` How long + have/has + S + Vpp + ... ?

`7.` I have never had such a delicious meal before.

`8.` I last saw him 8 days ago.

The last time I saw him was 8 days ago.

`-` S + haven't/hasn't + Vpp + ... + for time

`=` S + (last) + V-ed/c2 + ... + time ago

`=` The last time + S + V-ed/c2 + ... + was + time ago

`9.` I last took a bath on Monday.

The last time I took a bath was on Monday.

`10.` The last time Lucy visited me was in February.

`11.` How long is it since he had this car ?

`-` How long + have/has + S + Vpp + ... ?

`=` How long is it + since + S + V-ed/c2 + ... ?

Các công thức đổi HTHT - QKĐ

Structure 1: 

S + has/have + not + V3/ed + for/since + time 

--> S + last + V2/ed 

--> The last time + S+ V2/ed + was + time 

--> It is / has been + time + since + S+ (last) + V2/ed 

Structure 2: 

How long + has/have + S+ V3/ed?

--> When + did + S + V1?

--> How long is it + since + S+ V2/ed ?

Structure 3:

S + has/have + V3/ed + for/since + time 

--> S + started / began + to V / Ving 

--> It is / has been + time + since + S+ V2/ed 

Structure 4: 

S + has/have + not/never + V3/ed + ... before

--> This/It is the first time + S+ has/have+ V3/ed

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1.

- He hasn't been abroad before.

- He has never been abroad before.

2.

- We have learnt English for 5 years.

3.

- I haven't met her for 3 months.

- The last time I met her was 3 months ago.

- It's three months since I last met her. (xem lại gợi ý câu này)

4.

- This is the first time I have tried this kind of cake.

5.

- We haven't met for a long time.

- The last time we met was a long time ago.

6.

- How long have you bought it? 

7.

- I have never had such a delicious meal before.

8.

- I last saw him 8 days ago.

- The last time I saw him was 8 days ago.

9.

- I last took a bath on Monday.

- The last time I took a bat was on Monday.

10.

- The last time Lucy visited me was in February. 

11.

-  How long is it since he had this car?

`color{orange}{~MiaMB~}`