他的小心思英文表述为 "his hidden agenda"。这个短语用来描述一个人在做事情时，隐藏起来的真正目的或意图。它来源于拉丁语中的 "agenda"，意思是 "things to be done"，有时也被翻译为 "items of business"。
下面是一些例句及其中文翻译：
He always has a hidden agenda. 他总是有一个小心思。
I suspect that he has an ulterior motive for asking me to do this. 我怀疑他让我做这件事有另一个目的。
I can't figure out what his hidden agenda is. 我想不通他的小心思是什么。
It's clear that she has a hidden agenda in this matter. 很明显，她在这件事情中有一个小心思。
下面是一些例句及其中文翻译：
He always has a hidden agenda. 他总是有一个小心思。
I suspect that he has an ulterior motive for asking me to do this. 我怀疑他让我做这件事有另一个目的。
I can't figure out what his hidden agenda is. 我想不通他的小心思是什么。
It's clear that she has a hidden agenda in this matter. 很明显，她在这件事情中有一个小心思。