It is the first time that the local education authority ________ such strict requirements on    

going-to-school time for primary and middle school students. [ ]

A. makes        

B. has made      

C. had made        

D. made  

下列说法是往复式压缩机排气量不够的原因的是（）。

A.安全阀不严

B.入口堵

C.出口阀门开度过大

D.出口压力高