欲设计抗压强度为C30的普通混凝土，则其试配强度为( )MPa。
A．39.9
B．38.2
C．26.6
D．4b
参考答案：B
John was made _____ the truck for a week as apunishment. [ ]
A. to wash
B. washing
C. wash
D. to be washing
什么叫投影？点投影的特性是什么？
