To be ______ changing times you cannot have your body in the 21st century and your head back in the past.

A．in step with

B．in front of

C．together with

D．apart from

战国时期，关中地区农民创造了一种水渠开凿的新形式，至今还在新疆的干旱地区流行，该水渠是

A．郑国渠

B．灵渠

C．井渠

D．都江堰