fast比較級和最高級怎麼寫

fast的.例句：She climbed the staircase cautiously，holding fast to the rail（她緊緊地抓着欄杆，小心翼翼地爬樓梯）；Brindley was known as a very，very fast driver（衆所周知，布林德利是個喜歡飛車的人）。