— Our vacation cost a lot of money.

— Did it? Well, that doesn't matter ____ you enjoy yourselves. [ ]

A. unless

B. in case

C. as long as

D. so far as

表面活性物质减少时（）

A.肺泡表面张力不变而肺顺应性增加

B.肺泡表面张力降低而肺顺应性不变

C.肺泡表面张力增加而肺顺应性降低

D.肺泡表面张力降低而肺顺应性增加

E.肺泡表面张力不变，肺顺应性不变