diff --git a/TupleStudyTest/Readme.txt b/TupleStudyTest/Readme.txt
new file mode 100644
index 0000000..a5751f6
--- /dev/null
+++ b/TupleStudyTest/Readme.txt
@@ -0,0 +1,11 @@
+本项目使用.net framework 4.6.1, 因为项目引用的TupleStudy为 .net standard 2.0项目，
+而 .net standard 2.0 引用要求的最小.net framework版本为 4.6.1
+
+有一个问题：
+当xUnit.net 为 2.3及以上新版本时，出现测试异常：
+System.MissingMethodException : 找不到方法:“System.ValueTuple TupleStudy.ValueTupleStudy.CreateValueTuple()”
+
+xUnit.net 为 2.2及以下版本时，不出现异常，目前使用2.2
+
+原因是：xUnit.net的版本问题还是 ValueTuple的版本问题，或是.net standard 2.0 的问题，待有时间，慢慢验证。
+
diff --git a/TupleStudyTest/TupleStudyTest.csproj b/TupleStudyTest/TupleStudyTest.csproj
index efbd295..3b704f3 100644
--- a/TupleStudyTest/TupleStudyTest.csproj
+++ b/TupleStudyTest/TupleStudyTest.csproj
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="..\packages\xunit.core.2.3.0\build\xunit.core.props" Condition="Exists('..\packages\xunit.core.2.3.0\build\xunit.core.props')" />
   <Import Project="..\packages\xunit.runner.visualstudio.2.3.1\build\net20\xunit.runner.visualstudio.props" Condition="Exists('..\packages\xunit.runner.visualstudio.2.3.1\build\net20\xunit.runner.visualstudio.props')" />
-  <Import Project="..\packages\xunit.core.2.3.1\build\xunit.core.props" Condition="Exists('..\packages\xunit.core.2.3.1\build\xunit.core.props')" />
   <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
@@ -11,7 +11,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>TupleStudyTest</RootNamespace>
     <AssemblyName>TupleStudyTest</AssemblyName>
-    <TargetFrameworkVersion>v4.7</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <NuGetPackageImportStamp>
     </NuGetPackageImportStamp>
@@ -37,6 +37,9 @@
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="System.Core" />
+    <Reference Include="System.ValueTuple, Version=4.0.3.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
+      <HintPath>..\packages\System.ValueTuple.4.5.0\lib\net461\System.ValueTuple.dll</HintPath>
+    </Reference>
     <Reference Include="System.Xml.Linq" />
     <Reference Include="System.Data.DataSetExtensions" />
     <Reference Include="Microsoft.CSharp" />
@@ -45,15 +48,16 @@
     <Reference Include="System.Xml" />
     <Reference Include="xunit.abstractions, Version=2.0.0.0, Culture=neutral, PublicKeyToken=8d05b1bb7a6fdb6c, processorArchitecture=MSIL">
       <HintPath>..\packages\xunit.abstractions.2.0.1\lib\net35\xunit.abstractions.dll</HintPath>
+      <Private>True</Private>
     </Reference>
-    <Reference Include="xunit.assert, Version=2.3.1.3858, Culture=neutral, PublicKeyToken=8d05b1bb7a6fdb6c, processorArchitecture=MSIL">
-      <HintPath>..\packages\xunit.assert.2.3.1\lib\netstandard1.1\xunit.assert.dll</HintPath>
+    <Reference Include="xunit.assert, Version=2.3.0.3820, Culture=neutral, PublicKeyToken=8d05b1bb7a6fdb6c, processorArchitecture=MSIL">
+      <HintPath>..\packages\xunit.assert.2.3.0\lib\netstandard1.1\xunit.assert.dll</HintPath>
     </Reference>
-    <Reference Include="xunit.core, Version=2.3.1.3858, Culture=neutral, PublicKeyToken=8d05b1bb7a6fdb6c, processorArchitecture=MSIL">
-      <HintPath>..\packages\xunit.extensibility.core.2.3.1\lib\netstandard1.1\xunit.core.dll</HintPath>
+    <Reference Include="xunit.core, Version=2.3.0.3820, Culture=neutral, PublicKeyToken=8d05b1bb7a6fdb6c, processorArchitecture=MSIL">
+      <HintPath>..\packages\xunit.extensibility.core.2.3.0\lib\netstandard1.1\xunit.core.dll</HintPath>
     </Reference>
-    <Reference Include="xunit.execution.desktop, Version=2.3.1.3858, Culture=neutral, PublicKeyToken=8d05b1bb7a6fdb6c, processorArchitecture=MSIL">
-      <HintPath>..\packages\xunit.extensibility.execution.2.3.1\lib\net452\xunit.execution.desktop.dll</HintPath>
+    <Reference Include="xunit.execution.desktop, Version=2.3.0.3820, Culture=neutral, PublicKeyToken=8d05b1bb7a6fdb6c, processorArchitecture=MSIL">
+      <HintPath>..\packages\xunit.extensibility.execution.2.3.0\lib\net452\xunit.execution.desktop.dll</HintPath>
     </Reference>
   </ItemGroup>
   <ItemGroup>
@@ -64,9 +68,6 @@
   <ItemGroup>
     <None Include="packages.config" />
   </ItemGroup>
-  <ItemGroup>
-    <Analyzer Include="..\packages\xunit.analyzers.0.7.0\analyzers\dotnet\cs\xunit.analyzers.dll" />
-  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\TupleStudy\TupleStudy.csproj">
       <Project>{3bf11d95-1a17-444f-97a8-5536fcc8c015}</Project>
@@ -76,14 +77,20 @@
   <ItemGroup>
     <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
   </ItemGroup>
+  <ItemGroup>
+    <Content Include="Readme.txt" />
+  </ItemGroup>
+  <ItemGroup>
+    <Analyzer Include="..\packages\xunit.analyzers.0.7.0\analyzers\dotnet\cs\xunit.analyzers.dll" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
     <PropertyGroup>
       <ErrorText>这台计算机上缺少此项目引用的 NuGet 程序包。使用“NuGet 程序包还原”可下载这些程序包。有关更多信息，请参见 http://go.microsoft.com/fwlink/?LinkID=322105。缺少的文件是 {0}。</ErrorText>
     </PropertyGroup>
-    <Error Condition="!Exists('..\packages\xunit.core.2.3.1\build\xunit.core.props')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\xunit.core.2.3.1\build\xunit.core.props'))" />
-    <Error Condition="!Exists('..\packages\xunit.core.2.3.1\build\xunit.core.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\xunit.core.2.3.1\build\xunit.core.targets'))" />
     <Error Condition="!Exists('..\packages\xunit.runner.visualstudio.2.3.1\build\net20\xunit.runner.visualstudio.props')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\xunit.runner.visualstudio.2.3.1\build\net20\xunit.runner.visualstudio.props'))" />
+    <Error Condition="!Exists('..\packages\xunit.core.2.3.0\build\xunit.core.props')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\xunit.core.2.3.0\build\xunit.core.props'))" />
+    <Error Condition="!Exists('..\packages\xunit.core.2.3.0\build\xunit.core.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\xunit.core.2.3.0\build\xunit.core.targets'))" />
   </Target>
-  <Import Project="..\packages\xunit.core.2.3.1\build\xunit.core.targets" Condition="Exists('..\packages\xunit.core.2.3.1\build\xunit.core.targets')" />
+  <Import Project="..\packages\xunit.core.2.3.0\build\xunit.core.targets" Condition="Exists('..\packages\xunit.core.2.3.0\build\xunit.core.targets')" />
 </Project>
\ No newline at end of file
diff --git a/TupleStudyTest/ValueTupleStudyTest.cs b/TupleStudyTest/ValueTupleStudyTest.cs
index f419b80..d75e903 100644
--- a/TupleStudyTest/ValueTupleStudyTest.cs
+++ b/TupleStudyTest/ValueTupleStudyTest.cs
@@ -104,7 +104,7 @@ namespace TupleStudyTest
         [Fact]
         public void GetValueTuple_Test()
         {
-
+            Assert.Equal(1, 1);
         }
     }
 }
diff --git a/TupleStudyTest/packages.config b/TupleStudyTest/packages.config
index 1548b5e..881327b 100644
--- a/TupleStudyTest/packages.config
+++ b/TupleStudyTest/packages.config
@@ -1,11 +1,12 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="xunit" version="2.3.1" targetFramework="net461" />
+  <package id="System.ValueTuple" version="4.5.0" targetFramework="net461" />
+  <package id="xunit" version="2.3.0" targetFramework="net461" />
   <package id="xunit.abstractions" version="2.0.1" targetFramework="net461" />
   <package id="xunit.analyzers" version="0.7.0" targetFramework="net461" />
-  <package id="xunit.assert" version="2.3.1" targetFramework="net461" />
-  <package id="xunit.core" version="2.3.1" targetFramework="net461" />
-  <package id="xunit.extensibility.core" version="2.3.1" targetFramework="net461" />
-  <package id="xunit.extensibility.execution" version="2.3.1" targetFramework="net461" />
+  <package id="xunit.assert" version="2.3.0" targetFramework="net461" />
+  <package id="xunit.core" version="2.3.0" targetFramework="net461" />
+  <package id="xunit.extensibility.core" version="2.3.0" targetFramework="net461" />
+  <package id="xunit.extensibility.execution" version="2.3.0" targetFramework="net461" />
   <package id="xunit.runner.visualstudio" version="2.3.1" targetFramework="net461" developmentDependency="true" />
 </packages>
\ No newline at end of file