算术平均值中误差为观测值中误差的多少倍？（）
A.n
B.1/n
C.
D.
参考答案：D
下列示意图能如实反映亚洲地形与河流流向组合的是
A．①③
B．①④
C．②③
D．②④
I have a tennis and my friend Jim _____ two tennis rackets. [ ]
A. have
B. play
C. plays
D. has
