水合物在井口节流阀或地面管线中生成时，会使下游管线压力降低，造成供气中断或引起（）设备因超压破裂。
A、下游
B、上游
C、上下游
D、不确定
参考答案：B
—Which dress do you like best, Madam?
—Sorry, I can't decide now.[ ]
A. to buy which one
B. buy which one
C. which one to buy
D. which I should buy it
在最坏情况下，简单插入排序需要______次比较。
