Tom nereye gitmesi gerektiğini kesin olarak bilmiyordu.
- Tom didn't know for certain where he should go.
Tom yeni bilgisayarın ne kadara mal olacağını kesin olarak bilmiyordu.
- Tom didn't know for certain how much the new computer would cost.
For certain.
... don't want to laugh, because I'm quite certain that ...
... your children have to be more than a certain height to get ...