权数对算数平均数的影响作用只表现为各组出现次数的多少，与各组次数占总次数的比重无关。（）
参考答案：错
肩关节周围炎的病因病机包括（）
A.气血不足
B.外感风寒湿邪
C.外伤筋骨
D.痰浊阻络
E.气虚血瘀、瘀血阻络
— Which of these two English books will you borrow?
— I'll borrow _____ of them. Because they are very interesting. [ ]
A. either
B. all
C. neither
D. both
