He was observing the birds.

In physics, a meson is a type of particle made up of a quark and an antiquark.

My younger brother is the middle child in our family.

When he was a middle-school student, he used to study in the library every day.

He was always by my side as my helper.

Topography is a field of study that researches terrain and geographical features.

I will make dinner with my new wok.

He is explaining the fact of the expulsion of the Japanese in detail in that history book.

They started a movement to expel the Japanese.

I cooked today's dinner using fresh fruits of the sea.