Three days later, London housewife Luisa Carlill went down with flu. She was shocked. For two months, she had inhaled thrice daily from a carbolic smoke ball, a preventive measure guaranteed to fend off the flu-if you believed the advert, which she did.

请问: 这里的a preventive measure guaranteed to fend off the flu做什么成分？它是不是做advert的同位语？到这样的语序让我有点不理解了，同位语可以这样排语序吗？

与谁是同位语关系？

【答】a preventive measure guaranteed to fend off the flu 是名词词组，作前面这个句子 she had inhaled thrice daily from a carbolic smoke ball 的同位语。这个句子其实就是描述了一种预防流感的具体做法，而a preventive measure是它的同位语，把它总结为“预防措施”。因为同位语的两个成分之间是互为同位关系，所以，前句如果放在名词a preventive measure 之后的话，就是一个同位语从句。

后面破折号里面的if条件从句和谁有语义联系，有没有虚拟的意思，这个条件从句的主句在哪里？

【答】if you believed the advert, which she did 是条件从句，陈述语气，它与前句有语义联系。它的主句是 she had inhaled thrice daily from a carbolic smoke ball, a preventive measure guaranteed to fend off the flu，这个主句就是一个活生生的广告宣传 advert。

在 if you believed the advert, which she did. 中，which she did 是定语从句。这里，which 可以指代believed the advert，定语从句用 did 加强语气；或者 which 指代adevet，用did替代believed。

整个段落应该如何翻译？

【翻译】三天后，伦敦家庭主妇路易莎·卡莱尔患了流感。她很震惊。两个月来，她每天都从一个碳烟球中吸气三次——如果你相信这是广告宣传的话，这的确是一种预防流感的措施，而她却坚信不疑。（我把语序适当变通了一些）

整个句子是不是省略了一些内容？

我个人理解是: If you believed the advert-a preventive measure garanteed to fend off the flu, you would do the same as Luisa did. Because she believed the advert, she inhaled thrice daily from a carbolic smoke ball for two months.但这样是两句话，这段英文把这两句话糅合成了一句话，但这个糅合的过程我确实看不明白，望得到指点，当然这样的个人理解可能是错误的？

【答】网友的理解有失偏颇，可以参照我上面我的解答。