1.During his useful life ___________________________________________ (他却经常感到自己无用)
2.On account of the earthquake, _______________________________________(数千人无家可归)
3.She began to be worried ___________________________________________ (唯恐丈夫发生什么事)
4.Only by working hard______________________________________________(你才能通过考试)
5.Bob confessed to the police _________________________________________(他藏钱的地方).
答案：
1.he often felt he was useless
2.thousands of people were left homeless.
3.lest her husband should have met with some accident.
4.are you can pass the exam
5.where he had hidden the money