【11)Thesubjectoftheselectures____bythelecturecommittee.A)isannouncedB)havebeenannouncedC)areannouncedD)hasbeenannounced12)Ifoundanaspirinbottle____droppedonthefloorofDavid'sroom.A)wasB)hadC)hadbeenD)is13)Thego】

　　11)Thesubjectoftheselectures____bythelecturecommittee.

　　A)isannounced

　　B)havebeenannounced

　　C)areannounced

　　D)hasbeenannounced

　　12)Ifoundanaspirinbottle____droppedonthefloorofDavid'sroom.

　　A)wasB)hadC)hadbeenD)is

　　13)Thegoods____whenwearrivedattheairport.

　　A)werejustunloading

　　B)werejustbeenunloading

　　C)hadjustunloaded

　　D)werejustbeingunloaded

　　14)Ifone____bypride,hewillrejectusefuladviceandfriendlyassistance.

　　A)overcomesB)isovercomeC)hasbeenovercomeD)overcome

　　15)Mostenvironmentproblemsexistbecauseadequatemeasuresforpreventingthem____takeninthepast.

　　A)wasnotB)werenotC)werenotbeingD)hadnotbeen

　　16)Yououghttohaveputthemilkintherefrigerator,now____sour.

　　A)IsmellB)itissmeltC)itsmellsD)itissmelling

　　17)Aftertherace____,thecelebrationbegan.

　　A)hadbeenwonB)iswonC)willbewonD)hasbeenwon

　　18)Hewashereforalittlewhile,butIdon'tknowswhereshe____now.

　　A)isB)wasC)hadbeenD)hasbeen

　　18)Theyoungteacherhas____competent.

　　A)beenprovedtobeB)provedtobeC)beenprovedD)provedbeing

　　19)Pluto,theoutermostplanetofthesolarsystem,____photographicallyinMarch1930.

　　A)discoveredB)wasdiscoveredC)bydiscoveryD)whendiscovered

　　20)Togetabetterviewofthestage,____.

　　A)ourseatshadtobechanged

　　B)ourseatswerechanged

　　C)wehadtochangeourseats

　　D)ourseatswerechangedbyus