A Any intermediate to advanced student would benefit from a review of the usage, sentence position, and punctuation of however!
B However is also a conjunction or adverb, depending on the sentence position, that means in whatever manner or means or no matter how.
C The survey questionnaire, however long to be answered, was used for many years.
D We were told we would be discussing the new schedule during the meeting. However, our boss never brought it up once.