新建好项目后，把system.web.mvc.dll移除，重新选择本地C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 4\Assemblies下的system.web.mvc.dll，编译出现问题提示：“The type or namespace name 'Html' does not exist in the namespace 'System.Web.Mvc'”
切换回来对应新建时应用目录下的system.web.mvc.dll依然出现问题。
让view重新编译：
1,）修改web解决方案.csproj文件，
1.1,)设置MvcBuildViews属性为true;
<MvcBuildViews>true</MvcBuildViews>
1.2,)在</Project>前面加上以下内容:
<!-- To modify your build process, add your task inside one of the targets below and uncomment it.
Other similar extension points exist, see Microsoft.Common.targets.
<Target Name="BeforeBuild">
</Target>
<Target Name="AfterBuild">
</Target> -->
<Target Name="MvcBuildViews" AfterTargets="AfterBuild" Condition="'$(MvcBuildViews)'=='true'">
<AspNetCompiler VirtualPath="temp" PhysicalPath="$(WebProjectOutputDir)" />
</Target>
</Project>
,之后重新编译，问题就解决了。