SARS is an illness that can result in death unless left treated in time.
问题描述：
SARS is an illness that can result in death unless left treated in time.
答
leave的过去分词,省略了it's ,被处置.能不能讲一讲leave在这里的用法，为什么接treatedleft是leave的过去分词，这里是修饰省去的病人，除非病人被留下及时治疗。