单选题 She did not throw away the stockings until they were so ______ that they couldn't be mended anymore.
【正确答案】 B
【答案解析】短语辨析题。wear out“使筋疲力尽，使破烂不堪”，常以过去分词形式作表语； wear off“磨损、消耗”。根据句意，B为正确答案。句意：她把袜子一直穿到烂得无法再补才扔掉。