an electronic amplification system used as a communication system in public areas
同义词：public address system??/??P.A. system??/??PA system??/??PA
by the year; every year (usually with reference to a sum of money paid or received)
同义词：per annum??/??per year??/??each year??/??annually
英汉双解词典包含3185865条英汉词条，基本涵盖了全部常用单词的翻译及用法，是英语学习的有利工具。