________history of the American South is________history of suffering, also one of hope and success.[ ]

A. A; the      

B. The; the

C. A; a  

D. The; a

砌体的抗压强度最主要取决于（）。

A.块捌和砂浆的强度等级 

B.砂浆的强度等级 

C.灰缝的厚度 

D.砂浆中水泥用量