he has an ulterior motive for wanting to see her.
我的建议不是别有用心。
she definitely had an ulterior motive in offering to help.
她主动提出帮忙,肯定有不可告人的动机。
at that stage they were not yet an 「item」, and one is entitled to wonder whether there might have been an ulterior motive in her persuading him to stay.
那个时候,他们的关系还没有到「那个程度」,所以人们都想知道,凯特劝说威廉留在学校是不是有什么不可告人的目的。
people thought he must have an ulterior motive for wanting to help.
人们认为他想提供帮助一定是别有用心。
he has an ulterior motive for seeing her; he's going to ask for some money.
他来看望她是别有用心,他是来要钱的。
i have an ulterior motive in offering to help you.
我主动提出要帮助你是有私心的。