否则
Otherwise; or else
HSK 4HSK 3.0 · 4
A (what should be done/condition)，否则 + (S) + (就/会) + B (consequence)
否则 links an action or condition to the bad consequence of not meeting it: 快点儿走吧，否则要迟到了 'hurry up, or we'll be late'. The first clause often contains 必须, 应该, 得 or 要; the second often uses 就 or 会. Colloquially it equals 不然/要不然. With 幸亏…否则…, the sentence describes something narrowly avoided: 幸亏你提醒我，否则我就忘了.
HSK 4–5 gap fills and reading comprehension.
Examples
快点儿走吧，否则要迟到了。
Hurry up, or we'll be late.
你必须多练习，否则考试会不及格。
You must practice more, or you'll fail the exam.
出门记得带伞，否则下雨就麻烦了。
Remember your umbrella, or it'll be a hassle if it rains.
幸亏你提醒我，否则我就忘了。
Good thing you reminded me, or I'd have forgotten.
Exercises
1.我们得马上出发， 就赶不上飞机了。
2.你应该早点儿睡，否则明天 起不来。
3.Which sentence has the same meaning as “你得穿厚点儿，否则会感冒”？
4.幸亏你来了， 我一个人真不知道怎么办。