EntityFramework- Error in converting to to 'System.Collections.Generic

public Int32 QID_Get { get; set; }

public List<getChildQuestions> Child_Question_Get { get; set; }

public Int32 Active_Get { get; set; }

}
}
-----------------------------
namespace DAL
{
public static List<getChildQuestions> SubQuestions(Int32 QuestionID)
{

CPContext Context = new CPContext();

var SubQuestions = (from CB in Context .Question_Master
where CB.FKQID == QuestionID
select new getChildQuestions
{
qid = CB.QID,
qname = CB.Question
});

return SubQuestions.ToList();
}

---------
public List<GetCPModel> GetQuestionMaster(GetCPModel _Req)
{
CPContext Context = new CPContext ();

List<GetCPModel> _resReponseModel = null;
Int32 QuestionMasterCount = Context.Question_Master.Count();
if (QuestionMasterCount > 0)
{
_resReponseModel = (from p in Context.Question_Master

select new GetCPModel
{
QID_Get = p.QID,
Child_Question_Get = SubQuestions(p.FKQID),
Active_Get = p.Active,

}).ToList();

}
return _resReponseModel ;

}
}