I failed in the final examination last term and only then __________ the importance of study.
—Does he know how to work out the problem? —Yes, he has _______ a good idea to solve it.
The police stopped the car______ speed was more than 120km per hour.
The boss insisted that the task _______before 5 o’clock this afternoon.
We prefer______ alone rather than__________.
The collected money should be made good use __________the people who suffered a lot in the earthquake.