安装NEST的时候报了如下的错误：
PM> Install-Package NEST
Attempting to resolve dependency 'Elasticsearch.Net (≥ 5.5.0 && < 6.0.0)'.
Attempting to resolve dependency 'Newtonsoft.Json (≥ 10.0.0 && < 11.0.0)'.
Install-Package : 'Newtonsoft.Json' already has a dependency defined for 'NETStandard.Library'.At line:1 char:1
+ Install-Package NEST
+ ~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [Install-Package], InvalidOperationException
+ FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PowerShell.Commands.InstallPackageCommand
怎么回事那？
【解决方法】
升级Nuget
升级完成后，需要重新启动visual studio, 庵后再次安装就可以了。