Task 多线程执行

 var unitsTask = _basicDataService.GetUnitNamesAsync();
 var documentTypesTask = _basicDataService.GetDocumentTypesAsync();
 var organizationsTask = _basicDataService.GetOrganizationsAsync();

 await Task.WhenAll(unitsTask, documentTypesTask, organizationsTask);

 var units = await unitsTask;
 var documentTypes = await documentTypesTask;
 var organizations = await organizationsTask;