已知在一个样本中有50个数据,它们分别落在5个组内,第一、二、三、四、五组数据的个数分别为2,8,15,x,5,则x等于( ),第四组的频率为( )。
20;0.4
—Why are you still watching TV? Please go and do your homework.
—I ________ it. Can I watch it for another ten minutes?
A.finish
B.finished
C.have finished
D.am finishing
骨缝分离的诊断标准是()
A.>0.5mm
B.>1.0mm
C.>1.5mm
D.>2.0mm
E.>2.5mm