Abstract: This thesis attempts to explain the mismatch between the structural form and its deep expression exhibited by na rhetorical questions from the syntax-semantic interface. The speaker uses the na rhetorical question in conversation to express the mirativity toward the background proposition of the question, and then uses the local proposition to express the illocutionary negative assertion. The syntactic environment (intonational yes-no questions) of na rhetorical questions expresses the interrogative force, but the na rhetorical questions express the illocutionary negative assertion. The lexical factor of this force shift is na’s strong negative polarity, but its syntactic factor is the three dependencies triggered by na’s strong negative polarity: de-Q operation, covert movement and illocutionary negative assertion.