static void Main(string[] args) 
...{
ClassList listClass = new ClassList();
Console.writeLine("请输入第个字符串");
string a = Console.ReadLine();
Console.writeLine("请输入第二个字符串");
string b = Console.ReadLine();
foreach (string n in listClass.strList(a, b)) 
...{
Console.writeLine(n);
}
}
class ClassList 
...{
public List strList(string str1,string str2) 
...{
string stra = str1 + str2;
string strb = str2 + str1;
string strc = str1 + str1;
List listStr = new List();
listStr.Add(stra);
listStr.Add(strb);
listStr.Add(strc);
return listStr;
}
}