请根据左边所给的单词以正确的形式填空,
46.lockIlostmykeysandcouldn’t___thebox.47.experienceMarywasalreadyan___primaryschoolteacherattheageof24.48.threatTheirliveswerefrequently___bygasexplosion.49.performThefirstAmerican___ofthisoperawasin1926.50.courageItwas___ofMr.Stonetotryandsavethedrowningman.51.hopeHewasdisappointedsooftenthathebecame___.52.cruel___tochildrenoranimalsisacrimeinmanycountries.53.understandingJohnandMaryhada___,buttheyhavemadeitupnow.54.largeThefactoryisbeing___tomakeroomformoremachinery.55.eagerShecouldnotconcealher___forpraise.