句子主干:A new study shows +宾从
宾从中:主(unhappiness in middle age)+系词(is)+表语(a universal experience.)
also known as middle life (midlife) crisis:这是主语的定语,相当于定语从句,which is also known as middle life (midlife) crisis,先行词为unhappiness .
universal :形容词,全世界的,普遍的; experience此句为可数名,经历,
句意:一项新的研究显示,中年人的不幸福感,又被称为中年危机,是全世界普遍存在的现象.