VS低版本打开高版本常会出现的错：
The build tools for v140 (Platform Toolset = 'v140') cannot be found. To build using the v140 build tools, please install v140 build tools. Alternatively, you may upgrade to the current Visual Studio tools by selecting the Project menu or right-click the solution, and then selecting "Upgrade Solution...".
解决方法：
项目--属性--配置属性--常规，找到 平台工具集 ，把v140改为v120（Visual Studio 2013 (v120))