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 shouldn't have doubted you.
- Senden kuşkulanmamalıydım.
I doubt which sentence is grammatically correct.
- Dilbilgisel olarak hangi cümlenin doğru olduğundan kuşkulanıyorum.