【问题】 The number of these families has increased ______ 40 percent in the past ten years.
The number of these families has increased ______ 40 percent in the past ten years.
正确答案:C.by
题目解析:本题出自山东科技大学,国家开放大学人文英语1-1,由丰阳塔题库搜集整理。