required in the library regulations that any book borrowed __________ by due time, or the borrower will be fined.

This is a new problem _____in the popularity of private cars _____road conditions need to be improved [ ]

The novels written by the author sell best, but five years ago no one could have imagined how great a role hein the literary world

You’d better ____ in bed. It’s bad for youreyes.

Can he ________ it in English