在后面的父母英文可以翻译为 "parents in the back"。
这个短语来自于描述一种情景，即父母在后面，而不是在前面或者在旁边。
下面是一些例句：
The kids were running ahead while the parents were following behind. (孩子们在前面跑，父母在后面跟着。)
I looked back and saw my parents in the back, walking slowly. (我回头看到父母在后面，慢慢地走着。)
We were on a hike and my parents were lagging behind the group. (我们在远足，父母在群体的后面落后。)