阅读短文，回答问题

Our environment(环境) is important to us. What should we do to protect it?

Don't waste things. We should use things up. Don't throw away the paper when we use one side(面). We should use two sides of the paper. We don't always need to have new things. If your shoes are broken, repair them, please. Think over before we want to buy something new.

If you are cooking dinner and you need a butter sandwich, but there is no butter, you can have a cheese sandwich. In this way, you can use your cheese up.