--- Which of the following words has the same sound as the “s” in the word “cups”?

--- Let me see. That’s           .

A．boys

B．pens

C．desks

D．Girls

色谱柱的选择性可用“总分离效能指标”来表示，它可定义为：相邻两色谱峰保留时间的差值与两色谱峰宽之和的比值。( )