Theproblem________whenthestudentsrefusedtodotheirhomework.
Inthefuture,more______shouldbeplacedontheeducationoftheyoung.
Whenhesuddenly________upthesubjectofgeneticengineering,therewasanembarrassedsilence.
Shehadclearlyno________ofdoinganywork,althoughshewasverywellpaid.
It'smore________tobuyaseasonticketifyoutraveleveryday.