A second horse was in shock and died of heart attack while being treated by a veterinarian.
问题描述：
A second horse was in shock and died of heart attack while being treated by a veterinarian.
此句中的While being treated by .是怎么回事啊,我实在想不通.
答
这是【连词+分词短语】 作时间状语的用法
等于while 【it (=the horse) was】 being treated by a veterinarian.谢谢你，还想问一下，While是作什么，是连词，引出时间状语的。 英语中表时间的分词短语作“当。。。。时候”讲时， 可在前面加连词【when 或者while】再如：Be careful while crossing the street. 过马路的时候要小心。