添加项目文件。

ClassLibrary2.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.30621.155
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ClassLibrary2", "ClassLibrary2\ClassLibrary2.csproj", "{F4AB9468-30D3-4547-9A7F-7A6B512B4086}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{F4AB9468-30D3-4547-9A7F-7A6B512B4086}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{F4AB9468-30D3-4547-9A7F-7A6B512B4086}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{F4AB9468-30D3-4547-9A7F-7A6B512B4086}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{F4AB9468-30D3-4547-9A7F-7A6B512B4086}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {67E1B096-3625-4AD1-86AB-7C72CFC64567}
+	EndGlobalSection
+EndGlobal

ClassLibrary2/Class1.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace ClassLibrary2
+{
+    public class Class1
+    {
+    }
+}

ClassLibrary2/ClassLibrary2.csproj

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+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>f4ab9468-30d3-4547-9a7f-7a6b512b4086</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>ClassLibrary2</RootNamespace>
+    <AssemblyName>ClassLibrary2</AssemblyName>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+    <Deterministic>true</Deterministic>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System"/>
+    
+    <Reference Include="System.Core"/>
+    <Reference Include="System.Xml.Linq"/>
+    <Reference Include="System.Data.DataSetExtensions"/>
+    
+    
+    <Reference Include="Microsoft.CSharp"/>
+    
+    <Reference Include="System.Data"/>
+    
+    <Reference Include="System.Xml"/>
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Class1.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+ </Project>

ClassLibrary2/Properties/AssemblyInfo.cs

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+using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+// 有关程序集的一般信息由以下
+// 控制。更改这些特性值可修改
+// 与程序集关联的信息。
+[assembly: AssemblyTitle("ClassLibrary2")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("ClassLibrary2")]
+[assembly: AssemblyCopyright("Copyright ©  2020")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// 将 ComVisible 设置为 false 会使此程序集中的类型
+//对 COM 组件不可见。如果需要从 COM 访问此程序集中的类型
+//请将此类型的 ComVisible 特性设置为 true。
+[assembly: ComVisible(false)]
+
+// 如果此项目向 COM 公开，则下列 GUID 用于类型库的 ID
+[assembly: Guid("f4ab9468-30d3-4547-9a7f-7a6b512b4086")]
+
+// 程序集的版本信息由下列四个值组成: 
+//
+//      主版本
+//      次版本
+//      生成号
+//      修订号
+//
+//可以指定所有这些值，也可以使用“生成号”和“修订号”的默认值
+//通过使用 "*"，如下所示:
+// [assembly: AssemblyVersion("1.0.*")]
+[assembly: AssemblyVersion("1.0.0.0")]
+[assembly: AssemblyFileVersion("1.0.0.0")]