This phenomenon occurs cyclically.

This is my first question.

This toothpaste contains fluoride.

Śāriputra is one of the important disciples in Buddhism.

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

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

Transition elements play an important role in chemical reactions.

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

As if symbolizing the heat of summer, the cicadas started to sing.

I am working using a spreadsheet software.