You didn’t go to the party last night.
You didn’t meet your girlfriend.
If you had gone to the party last night , you would have met your girlfriend.
I didn’t pass the exam last semester. I didn’t study hard.
My wife was so angry with me. I forgot that yesterday was her birthday.
I had an accident last year . I drove the car very fast.
If I had checked the oil in my car carefully yesterday , I wouldn’t be in trouble now.
If I hadn’t gone to bed so late last night, I wouldn’t be tired today.
If it had rained so much last year, my crops would be better now.
Had I not driven the car so fast, I wouldn’t have had an accident last year.