I'm sorry you've been waiting so long but it'll still be some time Brian gets back.(·

问题补充：

Im sorry youve been waiting so long，but itll still be some time Brian gets back.(·北京)

A. before

B. since

C. till

D. after

答案：

(答案→)A. before

B. since

C. till

D. after

解析：考查状语从句。本题使用了“it be＋一段时间＋before引导的从句”句型，表示“在……之前还需要一段时间，一段时间之后发生某事”。后面句子的含义：不过Brian还要过一会儿才能回来。