~ねばならない (must, formal)

I have a large family to support.

In order to survive, polar bears must keep their body at the right temperature and store enough energy to last through meals that may be days or even months apart.

She had to study hard to catch up with her classmates.

She had to silently endure her own misfortune.

We must possess foresight that stays one step ahead of the times.

The train was packed, so she had to travel in second class and stand the whole way.

Next month, we have to make up for the losses.

Baseball players have to take the wind into account when catching a fly ball.

I must write down his address before I forget.

Whether we were tired or not, we had to keep walking.

We must confirm the facts before blaming her.

She must be home by nine at the latest.

She had to go herself.

She has to study hard to catch up with the rest of her class.

There are many things we need to discuss.

We must respect the elderly.

One of the parents must go to the meeting.

You must obey your parents.

I must finish this work by the day after tomorrow.

You must cross out every unnecessary word.

She has to pay the price of the book.