23、File system

295、on doing sth是做某事

294、有些动词后跟V-ing或跟toV意义不一样。

293、make a profit是赚钱

292、are based on是基于

291、be equal ()

290、We did it together; it was a( )() effort

289、But how do you know when you＇ve () the right boss?

288、In Professor Weinstein＇s class, for example

287、Though you () qualify for many positions

286、Her teaching experience qualifiesher for the job