I have to retake the exam.

I am looking forward to the day we meet again.

He became a prisoner of conscience because of his political beliefs.

This data requires appropriate processing.

We must consider appropriate measures for this problem.

I sent him a written request.

I wonder what this bento's mystery meat is made from.

It's difficult to solve this riddle.

He developed a submarine to explore the seabed.

It's difficult to solve this mystery.