var modelCb = new Ext.form.ComboBox({
            fieldLabel: '模型',
            hiddenName:'model',
            store: new Ext.data.SimpleStore({
                fields: ['Id', 'Name'],
                data : [
                    ['AL', 'Alabama', 'The Heart of Dixie'],
                    ['AK', 'Alaska', 'The Land of the Midnight Sun']
                ]
            }),
            valueField:'Id',
            displayField:'Name',
            hiddenName: 'op_objects',
            typeAhead: true,
            mode: 'local',
            triggerAction: 'all',
            emptyText:'-- 请选择 --',
            selectOnFocus:true
        });
modelCb.hide(); //这样不能隐藏fieldLabel