扫蒙金石颗粒粗细可根据需要而定,一般采用()筛子进行筛选。
A.10-25孔/cm2
B.25-50孔/cm2
C.50-75孔/cm2
D.75-100孔/cm2
参考答案:B
She a piece of chocolate and gave it to the poor little girl. [ ]
A. broke off
B. broke out
C. broke down
D. broke into
有效焦点是2.5mm×2.5mm,则实际焦点是()。
A.圆形的
B.椭圆形的
C.长方形的
D.梯形的