21)a) Talking my food I left for college.
b) While I was taking my food I left for college.
c) Having taken my food I left for college.
d) Taking my food I shall leave for college.
22)a) Meena seldom or ever refuses an invitation.
b) Meena seldom or always refuses an invitation.
c) Meena seldom or never refuses an invitation.
d) Meena seldom if never refuses an invitation.
23) a) I hope you will excuse my leaving early.
b) I hope you will excuse me leaving early.
c) I hope you will excuse mine leaving early.
d) I hope you will excuse leaving early.
24)a) Everybody knows that Rahul is nothing else but a cheat.
b) Everybody knows that Rahul is nothing else than a cheat.
c) Everybody knows that Rahul is nothing else except a cheat.
d) Everybody knows that Rahul is nothing but for a cheat.
25)a) He is one of the best policeman who has ever lived.
b) He is one of the best policeman who have ever lived.
c) He is one of the best policeman that have ever lived.
d) He is one of the best policeman that has ever lived.
Good Luck!