帮忙解决一下吧

[wl04071167]

float c,r;
string s2, s3;
r = timer1.Interval;
c = r/ 1000;
d = d + c;
s2 = d.ToString();
t =s2.IndexOf(".");
s3= s2.SubString(0, t+1);
运行时间.Text = s3;
RunBoard();
错误 1 “string”不包含“SubString”的定义，并且找不到可接受类型为“string”的第一个参数的扩展方法“SubString”(是否缺少 using 指令或程序集引用?) E:\C#\shexiangjiqiren\shexiangjiqiren\Form7.cs 228 20 shexiangjiqiren

[stonespace]

SubString应该为Substring，第二个s字母应该是小写，c#是大小写敏感的，

[stonespace]

float c,r;
string s2, s3;
r = timer1.Interval;
c = r/ 1000;
d = d + c;
s2 = d.ToString();
t =s2.IndexOf(".");
s3= s2.Substring(0, t+1);
运行时间.Text = s3;
RunBoard();