语法与词汇21.A code of ethics governing the behavior of physicians during epidemics did not exist until 1846 when it was ______ by the American Medical Association.
【正确答案】
B
【答案解析】本题考查动词辨析。根据did not exist until 1846可知，这部道德准则以前没有，直到1846年之后才有的，选项中，只有promulgate(颁布实施，公布(新法律等))符合语义，故答案为[B]项。rescind意为“废除，取消，撤销”。presuppose意为“以……为前提，预先假定”。depreciate意为“贬低；贬值，跌价”。