conjunction, verb · how about...?; used to introduce a suggestion or a proposal

要不我们去吃火锅吧？

conjunction · either... (or...); used to present two mutually exclusive alternatives

他要不就在办公室，要不就在会议室。

conjunction · otherwise; or else; used to indicate the consequence if the preceding condition is not met

快点，要不我们就迟到了。