题干

A total of 548 students fell ill ______ consuming milk and biscuits in schools in Northwest China's Qinghai province on Wednesday, local authorities said.
A.beforeB.whenC.afterD.while
上一题 下一题 0.64难度 单项选择 更新时间:2013-06-24 08:17:25

答案(点此获取答案解析)