单选题 --I'm going to Nanyue for a holiday this weekend.
-- ______ you are there, could you buy me some green tea?
[A] Because [B] While [C] Before

【正确答案】 B
【答案解析】[解析] 此题考查状语从句的连词。while和before都是时间状语的连词，但while是当…的时候，before是在…之前。