To be on the safe side, we should fill up the tank now, because we ______ run out of gas on the way.
25. When Jack reached the station the train ______ for ten minutes.
24. After ______ seemed a long time, Mr. Li stood up and broke the silence.
23. Allow others the space to voice their opinions, ______ they are different from yours.
20. Could ______ that have a say in the decision do us a favor about the problem?
19. Which do you enjoy ______ you weekend, doing sports or watching TV?