21.Thevacuumcleanerisavaluablelabor-saving______action.
A.deviceB.engineC.pieceD.instrument
22.Theflightwaspostponedbecauseoftechnicalproblemsandwasfinallycancelledlastweekwhena______wasdiscovered.
A.accidentB.defectC.damageD.defeat
23.Whenshewascrossingtheroad,shewasknockeddownbyamotor-carandlay______bytheroadside.
A.asleepB.thoughtlessC.unconsciousD.unaware
24.Thenovelshehaswrittenhaveshownhis______abilityasanauthor.
A.literalB.literallyC.literatureD.literary
25.Thereaderisurgedtobealeader,ratherthanafollower;torelyonhisownpower,ratherthanto______.
A.informB.conformC.deformD.reform
26.Hewouldmuch______itifyoucoulddohimthefavor.
A.awardB.applyC.appreciateD.anticipate
27.Ifour______iscorrect,thenthespace-craftshouldreachthemoononMonday.
A.calculationB.compositionC.communicationD.vision
28.SanFrancisco’sChinesecommunity,comprising67,000______isthelargestconcentrationofChineseoutsideofAsia.
A.visitorsB.workersC.adultsD.inhabitants
29.Wedidn’tcatchthetrainon______ofthetrafficcongestion.
A.basisB.chargeC.accountD.behalf
30.Thoughhehassufferedfromcancerforsomanyyears,itissostrangethathehas______tothepresentday.
A.deprivedB.survivedC.derivedD.revived