What really worries us is ______ the explorers can accurately locate themselves with the device in case of bad weather.
The football match ______, crowds of people poured out into the street.
The train ______ at seven o’clock and you’d better get to the station by half past six.
--- What happened to you? --- I was lost in the strange city; _______, it began to rain heavily.
Things came ______ after that. And now he has ______ student in Nanjing University.
Flight attendants usually need to arrive at the airport ______ before their flight leaves.