声明一个结构体如下: struct MyStruct{ public int x; public int y; public MyStruct(int i , int j){ x = i; y = j; } public void Sum(){ int sum = x+y; Console.WriteLine("the sum is " + sum); } } 则在Main 函数中使用以下语句后的结果为() MyStruct s1 = new MyStruct(1,2); s1.x = 2; s1.Sum();