简单的 Where，实现可能如下：
public static List<T> Where (this List<T> list,委托 delegate)
{
     List<T>  tmpList = new List<T> ();
     foreach( T p in list){
        if(delegate(p)){   
          tmpList.add(p);
         }
    }
     return tmpList;
 }

List<Person> persons = new List<Person> {"sds","sdsd"};

下面分别使用

Lambda表达式和匿名方法
List<Person>  tmp = persons.Where(p=>p.Name =="sds");
等于List<Person>  tmp = persons.Where(（Person p）=>p.Name =="sds"); //编译器
还等于List<Person>  tmp = persons.Where(Delegate(Person p) {
                                                                       return p.Name =="sds";
                                                                   })不过linq to object采用的是延迟查询；在看下面一例：