考研英语的某篇文章中，有这么一句话：

They worked until exhausted, lived with few protections and died young.

译文：他们工作到筋疲力尽，生活几乎无保障，年纪轻轻就命丧黄泉。

我的问题是：这里的until是连词还是介词？不管until是连词还是介词，后面怎么只接一个形容词exhausted？

如何理解until exhausted？谢谢老师！

【答】until是连词，不是介词，这实际上是一种省略现象。原句等于说：

They worked until they were exhausted, lived with few protections and died young.

until they were exhausted是“时间状语从句”，修饰worked。此外，worked，lived和died，是3个并列的谓语动词。

关于连词后面成分的省略，可参考：

http://www.yygrammar.com/Article/201501/3815.html