如何在此实例中保留克隆选择的选定值

Question

这将克隆下拉选项：var Task_Resource = $（'＃Resources'）。clone（）;然后我将它附加到#Task_table，如下所示。

但是如何克隆下拉列表并保留当前选择的选项？

$('#add_button').button({
    text: false,
    icons: {
            primary: 'ui-icon-plusthick'
        }
    }).click(function( event ) {
        event.preventDefault();

        $( "#dialog" ).dialog({
            autoOpen: true,
            show: {
                effect: "drop",
                duration: 500
            },
            hide: {
                effect: "drop",
                duration: 500
            },
            width: 350,
            modal: true,
            buttons: {
                "Add": function() {

                    var Task_name = $('#name').val();
                    var Task_pre = $('#Predecessor').val();
                    var Task_Start = $('#Start').val();
                    var Task_Duration = $('#Duration').val();
                    var Task_Duration_unit = $('#Duration_unit').val();
                    var Task_Resource = $('#Resources').clone();
                    var Task_Percent = $('#Complete').val();
                    var Task_Notes = $('#Notes').val();
                    var rowCount = $('#Task_table tr').length -1;
                    var dateStart = "Start_date_"+rowCount ;

                    $('#Task_table tbody').append('<tr class="row_sortable">' +
                     '<td class="project_table_cells">1</td>' +
                     '<td class="project_table_cells">'+Task_name+'</td>' +
                     '<td class="project_table_cells"><input title="" id="predecessor_" name="predecessor[]" class="predecessor" value="'+Task_pre+'" /></td>' +
                     '<td class="project_table_cells"><input title="" id="'+dateStart+'" name="Start_date[]" class="Start_date" value="'+Task_Start+'" /><td class="project_table_cells"></td>' +
                     '<td class="project_table_cells"><input title="" id="duration_" name="duration[]" class="duration" value="'+Task_Duration+'" /></td>' +
                     '<td class="project_table_cells"><select id="duration_unit_" onchange="" name="duration_unit[]" class="duration_unit"><option value="Days">Days</option><option value="Hours">Hours</option></select></td>' +
                     '<td class="project_table_cells"><select id="resources_" name="resources[]" class="resources">'+Task_Resource.html()+'</select></td>' +
                     '<td class="project_table_cells"><input title="" id="percent_complete_" class="percent_comp" name="percent_complete[]" value="'+Task_Percent+'"/></td>' +
                     '<td class="project_table_cells"></td></tr>');


                    $( this ).dialog( "close" );
                },
                Cancel: function() {
                    $( this ).dialog( "close" );
                }
            }
        });
    });