I have an ulterior motive in offering to help you.

我主动提出要帮助你是有私心的。

《牛津词典》

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。

youdao

A cynic reckons that people generally have an ulterior motive for what they do.

他们认为通常情况下，人们做事都是别有用心的。 对于他人的行为，他们往往充满怀疑与蔑视。

youdao

The Rwandans may also have an ulterior motive.

ECONOMIST: Kabila sends a message to the world: ��Buzz off��

With regard to both the business records and delayed notification sections of the Patriot Act (among others), the stance taken by the American Civil Liberties Union and like-minded critics seems to have an ulterior motive.

CENTERFORSECURITYPOLICY: Preserve the Patriot Act