Bùguǎn biérén zěnme wèn, tā dōu yīkǒu-yǎodìng zhè shì zìjǐ de zhǔyi.
No matter how others asked, she stuck to her story that it was her own idea.
Tips
history
From the late-Qing novel 官场维新记 chapter 10: 慧修一口咬定不认得李国斌 - the monk Huixiu 'clamped down' on his claim of not knowing the suspect. The metaphor is a dog biting shut and refusing to let go.
memory
Picture biting down (咬) on a statement like a dog on a bone - jaw locked shut (一口, 'in one mouthful'), no matter who tries to pry it loose.
