Which is mine?

The fulcrum is the point on which a lever rests or is supported and on which it pivots.

Q.E.D. stands for 'quod erat demonstrandum', which means 'that which was to be demonstrated'.

Which team will win?

This is the way in which it happened.

Which of you will try first?

This is the window which was broken by the boy.

Which joint did you dislocate?

Which do you like better, this or that?

Which prince is the legitimate heir to the throne?