A：Na+、Ba2+、NO3﹣、Cl﹣
B：K+、Na+、H+、Cl﹣
C：K+、NH4+、S2﹣、CO32﹣
D：Cu2+、Na+、Cl﹣、SO42﹣
Population
(million)
% of
Income(收入)
spent on food
Persons
Per room
% of houses
With water
And electricity
Telephones
per 100
people
children in
High schools
Tokyo
28.7
18
0.9
100
44
97
Mexico City
19.4
41
1.9
94
6
62
New York
17.4
16
0.5
99
56
95
St.Paul
17.2
50
0.8
67
Osaka
16.8
0.6
98
42
Seoul
15.8
34
2.0
22
90
Moscow
13.2
33
1.3
39
Bombay
12.9
57
4.2
85
5
49
Calcutta
12.8
60
3.0
2
Buenos Aires
12.4
40
86
14
51
Los Angeles
11.5
12
35
London
11.0
24
58
