She is a doctor, as was her husband.= She is a doctor, as her husband was.=She is a doctor, her husband was a doctor, too.

   【注意】表示“也一样”的意思时，as 引导的句子(叫做方式状语从句，不是定语从句)可以用倒装结构，也可以不用倒装结构；so 后面的句子必须用倒装结构。例如：

    She was very religious, as were most of her friends. 她 信宗教，她的绝大多数朋友也是这样。（摘自《牛津英语用法指南》第三版302.5节）    

    She plays the piano, as does her mother. 她和她母亲一样会弹钢琴。（或：她会弹钢琴，她母亲也会。）

    When at Rome do as the Romans do.（谚语）入乡随俗。

She is a doctor, as was her husband. 我认为as作为关系代词引导非限制性定语从句，并在从句中做表语，相当于as her husband was，as指代前面的doctor，这样分析正确吗？

回答如下：

She is a doctor, as was her husband,   as引导方式状语从句倒状结构，还可以采用不倒状结构，但是倒状结构现象更常见

倒装结构：as+谓语 +主语

The book was banned in the US, as were two subsequent books. 

这本书在美国遭禁，随后出版的两本也是一样。

陈述结构：as+主语+谓语

You must try to hold the tool as I do. 

你必须像我这样拿工具｡ 
Leave the things as they are. 

别动这些东西｡ 
We must do as the Party tells us (to do). 

我们必须按照党的指示办事｡