for DriveLetter := 'C' to 'Z' do begin DriveName := DriveLetter + ':'; DriveType := GetDriveType(PChar(DriveName)); if DriveType = DRIVE_CDROM then。。。。。。。。。。。 end; 请问 DriveLetter DriveName DriveType 是什么类型 就是说 var DriveLetter,DriveName,DriveType:这里怎么写?;