No one has _____ been able to trace the author of the poem.
Mostofhistime _____inreadingnovels.
Mostofthemistakes____becauseofcarelessness.
Theboysittingbythewindowistheonlyoneofthestudentswho _______fromthecountrysideinourschool.
Thestudentsinourschooleach_________anEnglishdictionary.
Thepairofshoes__________wornout.