Don't ask Mortimer what kind of rose he's growing. It's a thorny¹ question with him because he doesn't know the answer. A thorny question (literally, a question with thorns) is one that causes trouble, is controversial or sensitive. "I think what you are telling me is that a thorny question is a question that causes many problems," Mortimer said.

        千万别问莫蒂默他正在养的是什么花。对他来说这是个棘手的问题，因为他根本不知道答案。棘手的问题(照字面来理解，长刺的问题)具有争议性或者很敏感，或会引起麻烦。莫蒂默说：“我认为你跟我说的是个非常棘手的问题，它会带来不少麻烦。”