7.如果一個檔案系統(/dev/hda1)被掛載為唯讀，我們要如何把它重新掛載為可讀寫？(A)mount -owritable/dev/hda1(B)mount-oremount,rw/dev/hda1(C)mount-orw/dev/hda1(D)mount-o rw,defaults/dev/hda1