问题
选择题
He finished middle school .
A．in twenty in 1950s
B．at twenty in the 1950s
C．in twenties in the 1950s
D．at twenties in the 1950s
答案
答案：B
本题干语意为：他在二十世纪五十年代当他二十岁时就中学毕业了。at twenty表“二十岁”="at" the age of twenty;in the 1950s表“二十世纪五十年代”。