Had I known about this computer program, a huge amount of time and energy ________. [ ]

________the police thought he was the most likely one，since they had no exact proof about it，they could not arrest him.[ ]

If law and order as well as rules and regulations______, neither the citizen nor his property is safe.

.Jack came from a poor family, so his parents had to______a lot to pay for his education. (潍坊市)

Not until he failed in the last examination _________ he should have spent more time on study.