the frontiers of something idiom
C2 …的知识前沿；…的疆界
the limits of what is known or what has been done before in an area of knowledge or an activity
the frontiers of science and technology 科技前沿
英汉双解词典收录81607条英汉双解翻译词条，基本涵盖了全部常用单词的读音、翻译及用法，是英语学习的有利工具。