並前往https://academy.snapask.com/zh-hk/post/%E7%B7%B4%E7%BF%92-%E9%9B%86%E5%90%88%E8%A8%98%E6%B3%95%E9%A1%8C%E7%9B%AE-Set-notation-%E6%A6%82%E7%8E%87%E5%9F%BA%E7%A4%8E%E7%AF%87-af19fa485dd6