A disk scheduling mechanism in an operatingsystem causes the disk arm to sweepback and forth across the disk surface servicing all requests in its path. This is a

A． First Come First Serve

B． Shortest Seek Time First

C． Scan

D． None of the above

衣片的肩胛骨部位推胖，中腰伸开，后背袖窿归足，牵带敷集，后肩倾斜度配准，不宜过平是对中山服（）弊病的修止。

A、后背下沉

B、后中起涌

C、后背起吊

D、后背涟形