adj.别有用心的，不可告人的，隐秘的，秘密的，矢口否认的

He had an ulterior motive for his sudden generosity, which became clear later.
他突然慷慨解囊有着不可告人的目的，这在后来变得明了。
Her friendly behavior hid an ulterior intention to gain my trust.
她友好的行为背后隐藏着想赢得我信任的不纯动机。
The politician's speech was filled with promises, but many suspected ulterior motives behind them.
政客的演讲中充满了承诺，但许多人怀疑这些承诺背后有不可告人的目的。
I can't help but feel there's some ulterior reason why he's being so helpful.
我不禁觉得他这么乐于助人背后肯定有某种不可告人的原因。
The company's decision to invest heavily in that project had ulterior strategic considerations.
公司决定大量投资那个项目有其深远的战略考量。
Her offer to help seemed genuine at first, but her ulterior motive soon came to light.
她帮忙的提议起初看似真诚，但不久后她的真正意图就暴露了。
He always speaks in riddles, making it difficult to discern any ulterior meaning.
他总是说话拐弯抹角，让人难以捉摸背后的深意。
The gift was not without ulterior motive; it was a thinly veiled attempt at bribery.
这份礼物并非没有不可告人的目的，它是一个掩饰得很差的贿赂企图。
Her constant praise of her colleague's work had an ulterior aim of getting promoted over him.
她不断赞扬同事的工作，背后的目的其实是想借此获得晋升机会超过他。
The charity event, though seemingly altruistic, had ulterior financial gains for the organizers.
那场慈善活动表面上看是无私的，但实际上为组织者带来了不可告人的经济利益。