During the hike, a sudden rockfall occurred.

There was a rockfall from the mountain, so it was closed to traffic.

It seems there is a missing character in this sentence.

Uranus is the seventh planet in the solar system.

North Korea is a country located in East Asia.

He is interested in the history of the Old World.

Our team's performance is particularly good this year.

He was waiting for the guests in the reception room.

This chemical reaction occurs by the synthesis of two elements.

He is conducting an experiment to synthesize a new compound.