????Dictionary<string?? string>?????????
???????????м??????????????????????????
??????????????????Dictionary<[key]?? [value]>
??????????????????????????[key]???????????÷???
????????????????[key]??????????
????????????
1  //?????????
2
3 Dictionary<int?? string> dic = new Dictionary<int?? string>();
4
5 //?????????
6
7 dic.Add(1?? "one");
8
9 dic.Add(2?? "two");
10
11 dic.Add(3?? "one");
12
13 //??????????
14
15 string a = dic[1];
16
17 string b = dic[2];
18
19 string c = dic[3];
20
21 //1??2??3??????????“one”“two”“one”
22
23 //?????????з??????????a??b??c
24
25 //????????????????????????????????
26
27 //????????????