1. I have worked for the company since a year ago.
2. DH Lawrence, the famous novelist, was born one hundred years ago.
3. When did Catherina and Henry engage?
4. I haven't seen him since I was a  student. 
5. Alan hasn't visited his parents for ages. 
6. This will be the last time we have seen each other before I go.
7. By the time the train left, he has got to the station.
8. It is 10 years since the school was founded 10 years ago.
9. It was 6 months since she last had a relapse.  
``
Hiện tại hoàn thành:
DHNB: just, before, since, for, twice/three/several times, up to now, ever, How long, by the time
(+) S + has/have + V3/ed
(-) S + hasn't/haven't + V3/ed
(?) Have/Has + S + V3/ed
``
Quá khứ đơn:
DHNB: in + mốc thời gian trong quá khứ, yesterday, last year, last month,...
(+) S + V2/ed
(-) S + didn't + V
(?) Did + S + V