Fluoride is a mixture of chemicals that is sometimes added to drinking water and toothpaste because it is considered to be good for people’s teeth.
N-UNCOUNT
Fluoride is a mixture of chemicals that is sometimes added to drinking water and toothpaste because it is considered to be good for people’s teeth.
N-UNCOUNT
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012