back seat
noun [ C ] uk/ˌbæk ˈsiːt/ us/ˌbæk ˈsiːt/
(SEAT BEHIND DRIVER)
（汽车）后座
the seat behind the front seat of a car
(LESS IMPORTANT PLACE)
较低的地位，次要地位
a position of less importance
Nelson will never take a back seat to anyone. 纳尔逊绝对不甘人后。