必须 (bì xū): 〜しなければならない; 〜しなければならない; 義務的な; 必ず

We must finish this report before tomorrow.

You must wear a lab coat when entering the laboratory.

Learning a foreign language requires persistent practice.

He must go to bed early today because he has an exam tomorrow.

You don't have to come in person, but you must notify us in advance.