1. The last time she came back to her hometown was 4 years ago.
=> She hasn't come back to her hometown for 4 years.
The last time+S+Vqkđ= S+ has/have+ not+ PII
2. He started working as a bank clerk 3 months ago.
=> He has worked as a bank clerk for 3 months .
S+ started+ Ving= S+has/have+ PII
3. It has been 5 years since we first flew to Singapore.
=> We have flown to Singapore for 5 years.
It has been+ time+ since+ S+ Vqkđ= S has/have+ PII+ for+ khoảng tgian
4. I last had my hair cut in November.
=> I haven't had my hair cut in November.
S+ last+ Vqkđ= Shas/have+ not+ PII
5. The last time we called each other was 5 months ago.
=> We haven't called each other for 5 months.
The last time+S+Vqkđ= S+ has/have+ not+ PII
6. It is a long time since we last met.
=> We haven't met for a long time.
It is a long time since+ S+ last+Vqkđ= S+ has/have+ not+ PII
7. When did you have it?
=> How long have your had it?
When+ did+S+V?= How long+ have+ S+PII?
8. This is the first time I had such a delicious meal.
=> I have never had such a delicious meal before.
This is the first time S+Vqkđ= S+ have/has never+ PII
9. I haven't seen him for 8 days.
=> The last time I last saw him was 8 days ago.
The last time+S+Vqkđ= S+ has/have+ not+ PII
10. To day is Saturday. I haven't taken a bath since Wednesday.
=> It is Saturday since I have taken a bath
It's+ time+ since+S has/have+ PII