There are quite a few old books on the shelf, but _____ of them is useful to teenagers.

 —Shall I sit at this end of the boat or the other end? —If you keep still, you can sit at _____ end.

--Would you like this pair, or that pair? ---___ will do.

I’ve just seen no more than one copy of Gone with the Wind in the bookshop opposite. Tom, go and buy ________ back.

They are good friends.      is no wonder that they know each other so well.