Let me give this a try (please correct my mistakes):
本当ですか。この前先生がその形容詞について聞きまし た。新と旧はかんけいがあると言いました。でも新と古 はかんけいがありません。
Grr I know that's wrong, but I tried my best. I was trying to say, "Is that so? The other day I asked my teacher about those adjectives. He said that "新" and "旧" go together. But not "新" and "古.""
The best words in my vocabulary was to say they are related. But he said this because I was listing adjectives that are opposites and he said 古 doesn't pair up with 新...
So I wonder, has it only recently been removed as a jyouyou kanji? I won't get to ask him about this until Monday evening. ところで,"旧"と言う漢字の音読みは何ですか。