The number of people flying first class on domestic flights rose sharply in 1990, doubling the increase of the previous year.
A.doubling the increase of
B.doubling that of the increase in
C.double as much as the increase of
D.twice as many as the increase in(A)
E.twice as many as the increase of
08语法笔记上解释：不是说：今年的人数(total number)在增长以后，是去年增长人数（increase of the previous year)的两倍。
而是说：今年的增长(increase)是去年(increase)的两倍
这里doubling不是做伴随状语么？我记得prep07 上对伴随状语有这样的解释：
伴随状语的其中的一个特点：
伴随状语中动词的主语与主语中谓语动词的主语相同。 这样说double的主语不就是the number of people 么？那么翻译就是今年的人数(total number)在增长以后，是去年增长人数（increase of the previous year)的两倍。
