Science is more than a collection of unrelated facts; to be meaningful and valuable,________ must be arranged to show generalized character.

If a book is in French, ____ will be a challenge for me．

 --How is_______ going with you?　　　-- So so.

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

All the other boys have geography books and they will be ahead of me if I don’t get ______.