When it ______ advertising, consumers need to be educated about techniques used by advertisers.

We’d better_______ if we want to be on time．—OK．

Peter is going to look for a new job_____________ the company offers him more money．

Your mother _______ take a bus to work-Yes. But now she usually goes to work on foot.

Although the mysterious castle has disappeared for hundreds of years, it is believed that the _____ of the castle can still be seen at the top of the mountain.