说明：main1Teachers和main2Teachers 都是multiple的select,我想在某个事件中将main1Teachers中的选中的选项添加到main2Teachers中．但是如下的代码有错，怎么改都不成．错误是：缺少对象．可是我查了手册，没有缺少的对象啊．

function addMainTeacher() {
    var obj1 = document.addExamroom.main1Teachers;
    var obj2 = document.addExamroom.main2Teachers;
    for (var i=(obj1.length-1); i>=0; i--) {
        if (obj1.options[i].selected) {
        　　　obj2.options[obj2.length]=new Option(obj1.options
                                          [i].text, obj1.options[i].value);
～～～～～～～～～～～～～～～～～～～～～～～～～～～～错误提示在这行！

            obj1.options[i] = null;
        }
    }
}
--
FROM 218.249.53.*