我们必须在六点前到达，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.

你应该努力学习，否则你可能会考试不及格。

You should study hard, ___or ___else you might fail the exam.