Bunun seni bu kadar üzeceğini bilseydim bundan bahsetmezdim.
- If I knew it was going to upset you so much, I wouldn't have mentioned it.
Adresini bilseydim ona yazardım.
- If I knew his address, I would write to him.
... if we knew everything about you, we could provide services to you and we could know ...
... knew before. ...