我们必须在六点前到那里，否则我们会错过开头。

We must be there by six, ___or ___else we'll miss the beginning.

他告诉我快点，否则我会错过公交车。

He told me to hurry up, ___or ___else I would miss my bus.

完成你的作业，否则你不能出去玩。

Finish your homework, ___or ___else you can't go out to play.