If a lot of people say a film is not good , I won't bother to see it , or I'll wait _____it comes out on DVD. [ ]

A. whether    

B. after    

C. though    

D. until

短暂工休时，为了防止出现气带突然开裂或受到意外外力作用而产生破裂漏气，导致火灾爆炸事故的发生，氧气和乙炔气瓶阀门应处于怎样的状态？