Using ConvertAll and Aggregate in LINQ

string strImportResult = this.ImportResult.ToList()
     .ConvertAll<string>(Import => string.Format("<tr><td> 
         {0}</td><td>{1}</td><td>{2}</td><td>
         {3}</td></tr>"
         , Import.CustodianName
         , Import.ImportFile
         , Import.ImportStatus
         , Import.Particular))
    .Aggregate((ImportA, ImportB) => ImportA + ImportB);