不然 (bù rán): ไม่ใช่เช่นนั้น

We need to leave early, otherwise we'll miss the train.

You should wear more clothes, or you'll catch a cold.

Please put the book back in its place, otherwise others won't find it.

We must review carefully, otherwise we'll fail the exam.

You should go to bed early, or you'll be listless tomorrow.