If we build logically upwards from a few indubitables, the whole system must remain correct.
The indubitable effect of the potion convinced many unbelievers.
I doubt which sentence is grammatically correct.
- Dilbilgisel olarak hangi cümlenin doğru olduğundan kuşkulanıyorum.
I never doubted your words.
- Sözlerinden hiç kuşkulanmadım.