题目内容：
If you ____things that have already been used, you process them so that they can be used again.
参考答案：
选择题：If you ____ things that have already been used, yo
- 题目分类：国家开放大学-开放英语4
- 题目类型：选择题
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things that have already been used, you process them so that they can be used again.