题目

The soldiers cheered as the train crossed the border into Wisconsin.It had been a long trip from the south back to their homes in the north.      One of the men had a large red scar across his forehead. 36   had an injured leg that made it  37for him to walk.The third had   38  large eyes, because he had been sickwith malaria.      The three soldiers spread their blankets on the seats and tried to  39.It was a cold evening  40 it was summertime. George, the soldier with a fever, 41   in the night air. His joy in coming home was   42  with fear and worry.He knew he如图所示，右边两个小球的质量为m，木块质量为M，且M=2m，当两个小球在同—水平面做匀速圆周运动时，则M的运动情况是 [　　] A．向上运动B．向下运动 C．静止不动D．上下振动