A lot of farmers refused _____ the new machine, but the engineer persuaded them _____ his invention.[ ]

A. to use, try

B. to use, to try

C. use, trying

（）比例混合器，由配用的泡沫泵向其输送有压力的泡沫液，在标定的工况下，使泡沫液与水混合，形成泡沫混合液，输送给高倍数泡沫发生器。

A、贮罐式压力

B、压力输送

C、平衡压力输送

D、环泵式