近年来这方面的研究开发主要是围绕结构 、 合成 、 表征和催化反应等方面开展的. A class or static variable is usually a variable which is identical for all instances of a category.. So, for instance, should you wished a description for a class that description would be the identical for all instance of The category and could be accessed https://share.evernote.com/note/af6d420e-c0be-17be-4129-1eac6170b1fe