请教：关于double的词性

chengzhiying

OG11-4
A survey by the National Council of Churches showed that in 1986 there were 20,736 female ministers, almost 9 percent of the nation's clergy, double  the figure for 1977.

问：1 划线部分应该做同位语吗？double 的词性是名词吗？
    2  for 1977 为何不用 in 1977 ?

yoyo9012

double的词性是形容词

给出的解释3 a : being twice as great or as many <double the number of expected applicants>

我觉得in 1977和for 1977都可以， 只是in 1977中那个it指代不明。

chengzhiying

thank you so much. 清楚多了！