我正在嘗試按項目ID分組，以便我可以返回總和，但是當我嘗試使用First（）返回字段的值時，它只返回一個值。ASP.net c#項目嘗試返回字段的總和時，我使用LINQ的代碼返回正確的數字，但我似乎無法返回相應的字符串字段。我嘗試按2個字段分組，但這會返回太多記錄。public class JobsByDrivetime{private string pid;private double jobMinutes;private string jobEventType;public JobsByDrivetime(string pid, double jobMinutes,string jobEventType){    this.pid = pid;    this.jobMinutes = jobMinutes;    this.jobEventType = jobEventType;}public string Pid{    get { return pid; }    set { pid = value; }}public double JobMinutes{    get { return jobMinutes; }    set { jobMinutes = value; }}public string JobEventType{    get { return jobEventType; }    set { jobEventType = value; }}}List<JobsByDrivetime> ProjectbyDrivetime = new List<JobsByDrivetime>();ProjectbyDrivetime.Add(new JobsByDrivetime("0186975-0001", 439, "HR"));ProjectbyDrivetime.Add(new JobsByDrivetime("0186975-0001", 100, "HR"));ProjectbyDrivetime.Add(new JobsByDrivetime("0186975-0001", 180, "JR"));var projectBydrivetimeList = ProjectbyDrivetime.GroupBy(v => v.Pid) //(c => new { Pid = c.Pid, ProjectType = c.JobEventType }).Select(g => new{    Pid = g.Key,    ProjectMinutes = g.Sum(x => x.JobMinutes),    ProjectType=g.Select(x=> x.JobEventType).First()}).ToList();foreach (var D in projectBydrivetimeList){    shiftSummary.Add("<tr><td>" + D.Pid + "</td><td>" + D.ProjectType + "</td><td>" + D.ProjectMinutes + "</td></tr>");}輸出0186975-0001 HR 5390186975-0001 HR 180它（按項目類型）正確分組項目分鐘，但它僅顯示2個項目類型中的一種。我希望D.ProjectType在第一個是HR，在第二個是JR。我明白這是因為我正在使用First（）。