【题目】Languages across the world are becoming extinct______ endangered mammals and four times endangered birds.
A. at twice the rate of B. as twice fast as
C. twice faster as D. twice at the rate of
在线课程【答案】A
【解析】句意：世界上的语言消亡的速度是濒危动物灭绝速度的两倍，是濒危鸟类灭绝速度的四倍。分析可知固定短语at the rate of“以...的速度”，对比选项可知A选项采用“倍数+the+名词+of”的表达方法。故选A。