注水泥塞水泥浆配制量计算公式为()。
A.V=68.3/(r—1)
B.V=78.3/(r+1)
C.V=68.3/(r+1)
D.V=66.3/(r—1)
参考答案:A
防火密闭的作用是什么?
March is _____ month of the year.
A.three
B.third
C.the third
D.a third