XML序列化中含有List的情况，序列化到根节点下一层

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml.Serialization;
namespace Model
{
[Serializable]
[XmlRoot("Response")]
public class ResponseStorageQuery:List<Item>
{
//<Response>
//<Item>
// <Material_ID>物料号<Material_ID>
// <Material_Desc>物料描述</Material_Desc>
// <PO_Qty>入库数量</ PO_Qty >
// <DO_Qty>出库数量</DO_Qty>
// <Storage_Qty>在库数量</ Storage_Qty >
//</Item>
//<Item>
// <Material_ID>物料号<Material_ID>
// <Material_Desc>物料描述</Material_Desc>
// <PO_Qty>入库数量</ PO_Qty >
// <DO_Qty>出库数量</DO_Qty>
// <Storage_Qty>在库数量</ Storage_Qty >
//</Item>
//</Response>

}

[Serializable]
public class Item
{
public string Material_ID;
public string Material_Desc;
public string PO_Qty;
public string DO_Qty;
public string Storage_Qty;
}
}