The police tried to get some clues from the suspect,but he remained .
While the police have already done a lot of investigation, much evidence ___ __.
_____ on everyday practice, progress in English is a goal which can be achieved.
Look out! Keep away from the house, _____ the roof is under repair.
.You’d better get the problem solved as soon as possible ______ it becomes out of control.
—Happy Birthday, Ken! Did you invite Jason?—Yes, but he _____ a meeting in New York otherwise he wouldn’t be absent from my birthday party.