There is no decision yet ______ when the work might start.
They live on a busy main road. ______ must be very noisy.
They are good friends. _______ is no wonder that they know each other so well.
Does ________ matter if he can’t finish the job on time?
— I don’t know whether I should go abroad or not, Mum.— I leave _______ to your own judgment whether you should do it.
It used to be thought _____ the Earth was flat.