Transition elements play an important role in chemical reactions.

He can speak many languages.

Protists are single-celled organisms that live in water.

All his prophecies came true.

I am majoring in linguistics at university.

This entrance is the gateway to a profound path.

The source of this river is at the top of the mountain.

This area is rich in basalt.

I am learning how to use the present participle in English.

The present tense is used to express things that are happening now or general facts.