He is deeply interested in the theory of communism.

We need to find the real root of this equation.

I always laugh at his comical expression.

Einstein proposed the theory of relativity.

When the new year begins, I send a message to my friends saying 'ake ome koto yoro'.

He is an expert in theoretical physics.

In this restaurant, you can choose from a wide variety of menus as you please.

He lifted the heavy luggage while saying 'yokkoishoichi' as a joke.

There are no words to describe that beauty.

He is always grumbling about trivial things, it's really annoying.