Expertshavebeenwarning ofthehealthriskscausedbypassi... 国语站 题库 3.11W 大中小设置文本大小 问题详情: Experts have been warning of the health risks caused by passive smoking A. at a time B. at one time C. for some time D. for the time【回答】 C 解析:本题考查固定短语。从句中have been warning 可知,应用for some time 一段时间,at a time 每次;at one time 曾经。知识点:固定句型题型:选择题 TAG标签:#