as far as I know

Từ điển Oxford Advanced Learner 8th

as far as I ˈknow | as far as I can reˈmember, ˈsee, ˈtell, etc. idiom
used to say that you think you know, remember, understand, etc. sth but you cannot be completely sure, especially because you do not know all the facts
•As far as we knew, there was no cause for concern.
•As far as I can see, you've done nothing wrong.
•She lived in Chicago, as far as I can remember.
Main entry: ↑far_idiom