How can I move data from domain to business entity using 'select new' LINQ query [Resolved]

Linq query by using select new

public class Parent
{
   public ParentId{get;set;}
   public ParentName{get;set;}
   public List<Child> childs{get;set;}
}

public class Child
{
   public ChildId{get;set;}
   public ChildName{get;set;}
}


How can i move data from Domain Entity To Business Entity using Linq

List<Parent> parents=GetALLParentData();
List<ParentBE> parentBE=from p in parents
                        select new ParentBE
                         {
                            ParentId=p.ParentId,
                            ParentName=p.ParentName,
                            ChildBE.ChildId=p.Child.ChildId,
                            ChildBE.ChildName=p.Child.ChildName
                         }

long Child.ChildId
Error:
An object reference is required for the non-static field, method, or property 'Child.ChildId.get'

string Child.ChildName
Error:
An object reference is required for the non-static field, method, or property 'Child.ChildName.get'

How can move the data of List Of child domain entity to business entity along with parent domain entity to business entity using LINQ

[Resolved]