The doctor told me to take the medicine .
A. every fourth hours
B. each fourth hour
C. each four hours
D. every four hours
网友回答
A. every fourth hours
B. each fourth hour
C. each four hours
(答案→)D. every four hours
解析：
试题分析:考查固定短语。在英语中表达“每．．．”要用every +基数词+复数名词或者every+序数词+单数名词，所以D选项正确．句意：医生告诉我要每四小时服一次药。