Thank you for sending us ______ fresh vegetables of many kinds. You have done us _____ great service.[ ]

A. /; a            

B. the; a          

C. /;/          

D the; /

压缩机启动前盘车的目的是（）。

A.排出机内气体介质

B.排出机内油质

C.检查机内是否有卡滞和摩擦

D.检查压缩机润滑情况是否正常