Identify the sentence with correct adverb placement:
答案解析
**Core Concept**: Adverb position rules.
**Analysis**: Option D correctly places "never" between the auxiliary verb (have) and main verb (been).
**Error Options**: A ends with "very" improperly; B stacks adverbs unnaturally; C misplaces "usually" before "are".
**Key Point**: Mid-position adverbs typically follow auxiliary verbs.
正确答案:D