He threw a boomerang and watched it come back beautifully.

The Hachijō bulbul is chirping outside the window.

Gon's educational policy is very strict.

China adopts the principle of people's democratic dictatorship.

You need sandpaper to smooth this wood.

He bought paint to paint the house.

We have to fill in this hole.

All his stories are thought to be lies.

He is an expert in computational linguistics and is involved in the development of artificial intelligence.

He is an expert in comparative linguistics.