— So you were in the supermarket _____ you heard a strange sound, right?

— That's true. I ran out as quickly as possible. [ ]

A. when

B. while

C. then

D. which

车辆修理的基本原则是坚持预防为主和（）。

A、质量第一

B、信誉第一

C、技术与经济相结合