仿形打磨机的空气滤清器,每三个月或()进行更换,无使用记录的每三个月进行更换,有使用记录的按运转记录执行。
A.100小时
B.200小时
C.300小时
D.400小时
参考答案:A
. — Do you think there is anything ____ interest in the exhibition?
— Yes, I think some of the pictures are ____.
A.for; of help
B.of; of great help
C.in; of helpful
D.at; helpful
转子轴颈的圆度或圆柱度误差不符合要求时,可采用重新()或()的方法予以修磨。