Air is to us _____ water is to fish.

Have you ever ____.— No, never.

People now can know what is happening in the world quickly.—You’re right.With the help of computers，news can ___every corner of the world.

There is _____ “s” and _____ “u” in _____ word “bus”.

It’s ______ good idea to visit our old teachers on ______ Teachers’ Day.