Liquid oxygen is often used as rocket fuel.

Please respond as soon as possible.

Transitive verbs require an object that is directly moved by the subject.

Rare earth elements are essential materials for the manufacture of electronic devices.

An isotope refers to elements with the same atomic number but different numbers of neutrons.

Transition elements play an important role in chemical reactions.

Oxygen, which is one of the chemical elements, is necessary for us to breathe.

This area is affected by radioactive fallout from past nuclear tests.

He suddenly stood up and left the room.

He was on the verge of crying out of anger.