题目

— I put him down for a well-educated man. —______ ? — I mean that he's a well-educated man. A. I beg your pardon                 B. Speak louder, will you C. What’s that                  D. Will you repeat word for word   答案：A某一回旋加速器，两半圆形金属盒的半径为R，它们之间的电压为U，所处的磁场的感应强度为B，带电粒子的质量为m，电荷量为q，则带电粒子所能获得的最大动能为          。