She was always well____ the rest of her class in English.    [ ]

A. in front of        

B. ahead of    

C. ahead from        

D. in the front of

液压系统的压力分级有低压、中压、中高压、高压、超高压五种，当系统压力为＞25－80kg/cm²时，称（）。

A、中压

B、中高压

C、高压

D、超高压