The thesis, based on Helen Spencer-Oatey's rapport management which is a dynamic theoretical perspective, investigates how the speaker makes the transition of linguistic forms in terms of politeness degree according to dynamic assessments of interactional wants, face sensitivities, and behavioral expectations and specific contexts. Then we are safe to infer the transitional mechanism of impolite utterances. The transitional mechanism of impolite utterances can be applied to college English teaching, which raises students' pragmatic awareness. It can also lead them to consciously transform their intuitive utterances into more polite ones whose meanings are equivalent, and complete daily communicative activities smoothly.