(~s)
If someone has an ~, doctors use special equipment to measure the electric currents produced by that person’s heart in order to see whether it is working normally.
N-COUNT
(~s)
If someone has an ~, doctors use special equipment to measure the electric currents produced by that person’s heart in order to see whether it is working normally.
N-COUNT
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012