Many people can’t learn any lessons from the mistakesthey’ve made _____ they get hurt somehow.

Do you know __________ this evening— Let me see. Oh, in two hours.

We all demanded the new type of machine ____________ put into use as soon as possible.

Philip has gone to New Zealand．Oh，can you tell me________

Our classroom is on the _____ floor. We can hear the students singing on the fourth floor.