她以平淡的语气给出了这个毫无激情的回答。

She gave a ___passionless reply in a monotone voice.

他们的关系看起来缺乏激情，没有任何欲望的火花。

Their relationship appears ___passionless, lacking any spark of desire.

他的演讲缺乏激情，让人昏昏欲睡。

His ___passionless speech made everyone feel sleepy.