A:m>2x+2
B:m=2x+2
C:x︰m︰n=1︰2︰1
D:m︰n=2︰1
某批乒乓球的质量检验结果如下:
抽取的乒乓球数n
50
100
200
500
1000
1500
2000
优等品频数m
47
95
189
478
948
1426
1898
优等品频率mn
a
0.95
b
0.956
0.948
0.951
0.949
It is generally believed that mutual understanding ______ a happy marriage and life.