Englishfor English speakers
nitrogen
Noun
—
Nitrogen is a colourless gas that has an atomic number of 7 and the symbol N.
The air we breathe is mostly made of nitrogen.
Nitrogen does not react very easily.
Liquid nitrogen is used to keep other things very cold.
must
Verb
—
Must is usually used to tell someone they have no choice about doing something because it is important or because of a rule or law.
She must get her medicine soon or she will die.