c#怎么设置一个字符串中某个字符的颜色

this.lblText.Style["color"] = "#777;font-size:12px";
lblText.Text = "录入完成，总共有<b style=\"color:red\">" + CSVHelper.CountSum + "</b>条，录入成功<b style=\"color:red\">" + CSVHelper.ThreadSum + "</b>条";