There are a few problems.

Special relativity is one of the fundamental theories of physics.

This software has forward compatibility.

This software maintains backward compatibility.

Whenever he faced a difficult situation, he always said, 'The best of the Thirty-Six Stratagems is to run away.'

The Tōhoku earthquake off the Pacific coast, which occurred on March 11, 2011, was the largest earthquake in Japanese history.

He worked hard without giving up.

He does yoga every day to increase his body's flexibility.

This is a model of a mutetrahedron.

This mutetrahedron has a very unusual shape.