Since the introduction of the new technique, the production cost______greatly.

A．reduces

B．has been reduced

C．is reducing

D．is reduced

我国著名的优良牲畜品种三河马和三河牛产于            [ ]

A．青藏高原的河谷地区        

B．新疆天山山脉的山麓地区

C．内蒙古高原的东部地区      

D．黄土高原的北部地区