—What about the film you saw last night?
题型：选择题
问题：
—What about the film you saw last night?
— .I might as well have stayed at home and had a good rest.
A．It couldn’t have been any better
B．It couldn’t have been any worse
C．It was the best one
D．There was no better one
，底边cd长
，放在垂直于纸面向里的待测匀强磁场中，且线圈平面与磁场垂直.当线圈中通入如图方向的电流
时，调节砝码使天平平衡．若保持电流大小不变，使电流方向反向，则要在天平右盘加质量为
的砝码，才能使天平再次平衡.则磁感应强度
的大小为
