559.Scientists are working _____ time in order to find a cure for bird flu as soon as possible.
A.on
B.ahead of
C.around
D.against
560.After the robbery,the shop fixed an alarm system ______ further losses.
A.for
B.against
C.from
D.to
559.答案是D;against time 与时间竞争；ahead of time 提前。
560.答案是B;考查介词在具体语境中的运用。句意:抢劫俺发生后，这家店按照了报警系统以防更多的损伤。此处against意为:防备，为…而准备。
