整齐可比性
参考答案:
任意两因素的各种水平的搭配在所选试验中出现的次数相等
Tom is an American boy. He can speak________ Chinese. [ ]
A. a little
B. a lot
C. many
D. very much
关于伸直型肱骨髁上骨折的叙述哪一项是错误的:()
A.骨折线由前上方斜向后下方
B.近端向前移位,远端向后上方移位
C.也可向侧方移位
D.侧方移位常不稳定
E.可损伤正中神经和肱动脉