common occurrence; encountered with many times; often (/frequently) seen ; nothing new; occur repeatedly
❍ 新制度的巩固过程和旧影响的消失过程，都不是直线的，它们的某种波浪式的起伏现象，在历史的转变时期是～的。The consolidation of a new system and the dying away of the old influences do not operate in a straightforward fashion but occur repeatedly in the form of an undulating movement at turning points in history.
屡见不鲜
common occurrence;nothing new
考试作弊～。Cheating in examinations is a matter of common occurrence./婚前同居，已是～。There is nothing new about premarital cohabitation.
屡见不鲜lǚ jiàn bù xiān
屡：屡次，不止一次；鲜：新鲜、新奇。多次见到，并不新鲜。nothing new, common occurrence, common sight, be not rare