单选题 Lucy knew nothing about it ______ her sister told her.
A. because B. until C. since

【正确答案】 B
【答案解析】[详细解答] 此题考查时间状语从句。not…until…意为直到……才，nothing一词是否定的意思，此句可转化为：Lucy didn't know anything about it until her sister told her。