1.虽然我们年纪小，我们仍然能为保护环境做一些事情。
    _______ we are young, we can still _______ _______ to protect the environment.  
2.怀特一家在扔垃圾之前总是要将它们分类。
   The Whites always sort the waste before _______ _______ ______.
3.在你买新东西之前，想一想是否真的有必要。
   Think whether it is really necessary before you buy _______ _______ .
4.为了节约资源，我们要爱护我们的物品以便它们能长时间使用。
   In order to save resources, we should look after our things _______ _______ they can last a long time.
5.用陶瓷杯比用纸杯好，因为它可以重复使用。
   _______ _______ to use a china cup than a paper cup because it can be used again.