Many people have come to realize they should go on ________ diet and make room for ________ exercise．

A．a; 不填

B．the; an

C．the; the

D．不填; an

露天()堆垛着火后，易形成堆垛内外一起燃烧。

（A）金属 

（B）棉花 

（C）原油 

（D）粮食