In the library new books have to be ___ before they are put on shelves for reader’s use.

Helen was much kinder to her youngest son than to theothers, ______, of course, made the others envy him.

This chapter is so difficult to ______ that I shall have to read it again later.

The man didn’t know _________ the thief broke into the house and stole all his valuable things

knew he failed in the final exam the moment I ______ him crying alone in the classroom.[ ]