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. before
B. when
C. after
D. while
网友回答
A. before
B. when
(答案→)C. after
D. while
解析：当地政府说，中国青海省的西北部，有548名学生在学校吃了饼干，喝了牛奶之后生病。Before在……之前when当……时候after在……之后while在…..期间，根据题意，故选C。