chemical
举一反三
- A chemical is any aspect of a substance which is only seen by means of a chemical reaction (反应).
- A chemical compound that contains two atoms of oxygen and one atom of another chemical element is called ______
- To identify a substance, chemists observe two distinct types of , physical and chemical, which are related to physical and chemical that matters undergoes.
- Nuclear rockets, in contrast to their chemical
- Water is a kind of chemical substance.