Time_____,thecelebrationwillbeheldasscheduled.
A、permit
B、permitting
C、permitted
D、permits
TheClarkshaven’tdecidedyetwhichhotel_____.
A、tostay
B、istostay
C、tostayat
D、isforstaying
John'sscoreonthetestisthehighestintheclass;（）helastnight.
A、muststudy
B、shouldhavestudied
C、musthavestudied
D、issuretostudy
ProfessorJohnsonissaid_____somesignificantadvanceinhisresearchinthepastyears.
A、havingmade
B、making
C、tohavemade
D、tomake
Ifthedrugproveseffectiveinhumantrials,itcouldenhancetheeffectivenessofexistingAIDSdrugsin________.