使用Webdriver等待运行代码时出错

Question

在下面的selenium webdriver代码中，我收到了wait.until的错误 在调试模式下运行程序时 参考如下
IEEXECRemote
nunit.framework
Selenium.Webdriverbackedselenium
系统
System.data
的System.Xml
Thoughtworks.selenium.core
的webdriver webdriver.support

我得到的错误是这样的

Error   4   The type 'System.Func`2<T0,T1>' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.    F:\AutomationProjects\Selenium\Webautomate\Webautomate\DragandDropWebElement.cs 37  1   Webautomate

如何解决此错误？我是否可以参考添加到解决方案

我尝试添加System.core，但它说它已经存在并且不接受它

我在Google上做了一些研究，但无法解决问题，因此我在这里问。

using System;
    using System.Collections.Generic;
    using System.Text;
    using System.Threading;
    using OpenQA.Selenium;
    using OpenQA.Selenium.Firefox;
    using OpenQA.Selenium.Chrome;
    using OpenQA.Selenium.IE;
    using OpenQA.Selenium.Support.UI;
    using System.Collections.ObjectModel;
    using OpenQA.Selenium.Interactions;
    using OpenQA.Selenium.Interactions.Internal;


    namespace Automation
    {
        class DragandDropWebElement
        {
            static void Main(string[] args)
            {

    IWebDriver driver=null;
    try
    {


        driver = new FirefoxDriver();
        driver.Url = "http://www.google.co.in";

       driver.Manage().Timeouts().SetPageLoadTimeout(TimeSpan.FromSeconds(10));
       driver.Manage().Timeouts().SetScriptTimeout(TimeSpan.FromSeconds(10));
       driver.Manage().Timeouts().ImplicitlyWait(TimeSpan.FromSeconds(20));



       WebDriverWait wait = new WebDriverWait(driver, TimeSpan.FromSeconds(10));
    wait.Until(ExpectedConditions.TitleContains("Google"));
                string  title = driver.Title;
        System.Console.WriteLine("Title is :" +title);

       Actions builder = new Actions(driver);

       IWebElement e1 = driver.FindElement(By.CssSelector("#gbqfq"));
       IWebElement e2 = driver.FindElement(By.PartialLinkText("Hindi"));
       bool displayed = e1.Displayed;
        bool enabled  = e1.Enabled;


        string text = e1.Text;


       System.Console.WriteLine(" The inner Text of e1 is : " +enabled ); 


    }

     catch(Exception e){

       Console.WriteLine("Exception ******"+e.ToString());

     }

                finally{
                Thread.Sleep(2000);
                driver.Quit();
                Console.ReadLine();
                }


            }
        }
    }