单项选择题
A.m0/(9i) B.m0/(8i) C.m0/(11i) D.m0/(4i)
A.硅酸三钙 B.硅酸二钙 C.铁铝酸四钙 D.铝酸三钙
A.An=b×t-dt/2 B.An=b×t-πd2t/4 C.An=b×t-dt D.An=b×t-πdt