Задание 
Match the words with the definitions.
Write the number of the definition near the word.
Calcium [ ]
Fluoride [ ]
Bacterium [ ]
Condition [ ]
A chemical substance sometimes added to water or toothpaste in order to help keep teeth healthy.
The particular state that something or someone is in.
A type of very small organism that lives in air, earth, water, plants, and animals, often one that causes disease.
A chemical element that is present in teeth, bones, and chalk.