—It's a wonderful way of getting to see Italy, and it also________cost very much.

— Terrific. [ ]

A. needn't  

B. mustn't  

C. couldn't 

D. shouldn't

计算锥顶角为120°、锥高400mm、厚度为1.5mm钢板卷制的正圆锥形护罩的质量（可不考虑板厚处理）。