The air in Rizhao is getting much _____ now than a few years ago .
We should help those people who are ____.
It’s ____ knowledge that the Nile is the longest river in the world.
Mickey Mouse is one of many children’s favourite cartoon character. Its pictures are ____, on school bags, desks, and so on.
Last Saturday was Mary’s birthday.
If parents leave their children on own, do you think the home is tidy or untidy when they return?