Which sentence demonstrates correct inversion structure?
答案解析
**Core Concept:** Inversion with negative adverbials (倒装句).
**Analysis:** Negative adverbs like 'never' at the beginning of a sentence trigger subject-verb inversion. Option B correctly uses 'have I seen' (auxiliary verb + subject + main verb). Options A/C lack inversion. Option D incorrectly mixes past tense 'saw' with 'did' auxiliary.
正确答案：B