[一个萝卜一个坑](%E4%B8%80%E4%B8%AA%E8%90%9D%E5%8D%9C%E4%B8%80%E4%B8%AA%E5%9D%91.md) [可以重复使用](%E9%87%8D%E5%A4%8D%E4%BD%BF%E7%94%A8.md)