21．You know, ________ knowledge of ________computer is necessary to a secretary(秘书).
A．a; / B．the; the C．the; / D．a; a
22．The room was empty_______ a computer and a desk.
A．except B．without C．except for D．besides
23．A big earthquake________ Pakistan on October 8 , 2005, ________ over 70,000 people.
A．strikes; killing B．struck; killing C．knocked; killed D．hit; kills
