关于double与increase的问题

yay

BY87页有一道题，

Founded in1983,the magazine increased its circulation more than double since then, and its advertising.

answer: has since more than doubled its circulation

读起来怪怪的，不晓得是个怎样的句式，哪位高手可以帮忙分析一下，

然后题目的B has since increased its circulation more than double. BY上说是错的，因为包含增加的意思，但是查字典，double的确是有形容词“两倍的”的意思呀~~希望高手指点·~~

yay

为什么没有人回答呢？？？？

lauren831

double是动词，vi&vt,排除B;