下列实数中．是无理数的为( )
A：0
B：227
C：3.14
D：2
——_________do you write a letter to your father?——I seldom or never do that now. Instead, I call or e-mail him almost every day.
分组/分
频数
频率
50≤x＜60
6
0.12
60≤x＜70
a
0.28
70≤x＜80
16
0.32
80≤x＜90
10
0.20
90≤x≤100
c
b
合计
50
1.00
