They had talked for a few minutes _____ they found they were of different opinions.

A、unless

B、while

C、before

D、once
出自:大学英语(C)252

完成拼图验证

按住下方滑块,将拼图拖到缺口处后松开。

拼图背景,将小拼图拖到缺口处
向右拖动滑块