英语题，第一段划线句，不是一个完整句子，它在句子做什么成分呢？

Question

英语题，第一段划线句，不是一个完整句子，它在句子做什么成分呢？文中有些空，不过不影响阅读整个句子。

Answer 1

According to Samantha Collier,the chief executive, Fine Fitness remains strong and is on track to reach its target of 100 clubs within three years, its strategy unaffected by the apparent slowing down of the economy.
这个是独立主格结构作状语。
前面一句话已经有完整的主谓宾，因为中间没有连词连接，逗号不能连接两个完整的句子，所以这个句子作为分句，其实这个也是一个定语从句变式过来。你可以看成是：
According to Samantha Collier,the chief executive, Fine Fitness remains strong and is on track to reach its target of 100 clubs within three years, whose strategy is unaffected by the apparent slowing down of the economy.