题目

—Do you have any idea what Paul does all day?  —As I know, he spends at least as much time playing as he _______. A. writes                      B. does writing       C. is writing           D. does write 答案：B19．某几何体的三视图如图，若该几何体的各顶点都在一个球面上，则此球的表面积为100π；（2R=$\frac{a}{sinA}$，其中R为三角形外接圆半径）