【---Doyoubelievetherearealiens?---i'mafraidnot.idon'tthinkaliens____inspace.a,canfindb,canbefoundc.canbefoundedd,can'tbefoundMary_____manysongsataparty.a.heardsingb.heardtosingc,washeardsingd,washeardtosinganacci】

　　---Doyoubelievetherearealiens?

　　---i'mafraidnot.idon'tthinkaliens____inspace.

　　a,canfindb,canbefoundc.canbefoundedd,can'tbefound

　　Mary_____manysongsataparty.

　　a.heardsingb.heardtosingc,washeardsingd,washeardtosing

　　anaccident_____onthisroadlastweek.

　　a,hasbeenhappenedb.washappenedc,ishappenedd,happened

　　he______somepiecesofadvice,buthe______tothem.

　　a.gave,didn'tlistenb.wasgiven,wasn'tlistened

　　c.give,wasn'tlistenedd.wasgiven,didn'tlisten

　　astory____byGrannyyesterday.

　　a.wastoldusb,wastoldtousc.istoldusd,toldus

　　itisreportedthatChina'slargestmuseumofmodernart___attheendof3010.

　　a.isbuiltb.willbebuiltc.buidsd,willbuild

　　theroom____,butnowit'sdirtyagain.

　　a,wascleanedb,iscleanedc.cleadedd.cleans

　　---nowcomputers_____inmanyways.

　　---yes,theyareveryuseful

　　a.useb,willusec.areusedd,beused

　　don'tworry.Mary_____thenewsalready

　　a,wastoldb,willbetoldc.hasbeentoldd,istold

　　you____smokeinthelibrary.

　　a,arenotallowedtob,weretoallowedc,arenotallowed

　　d,werenotallowedto