如何使用dom控制表单

（背景：我们学校最近发疯，要求学生网上填写好多表单，一个表单50个选择题，人要发疯了，于是我想写一个脚本自动勾选，分析了一会，发现自己的dom知识不够，于是求教cadn的大佬们如何使用js和dom控制下面的表单）
<form action="/t/student/submitsj" method="POST" id="cesj" name="cesj">      
                    <div class="ec_content ep_content">
                    
                  
                   
                   
                                             <!-- 单选 -->
                        <div class="ep_topic">
                            <div class="ep_t_topic">
                                <div class="ep_tt_num">1</div>
                                <div class="ep_tt_topic"><b>【单选】</b><span><p><span style=";font-family:宋体">毕业生违约后没有落实新工作单位的毕业生户口和档案怎么办？（&nbsp; &nbsp;）</span></p><p></p></span></div>
                            </div>
                            <ul class="ep_t_ul">
                                <li><label>
                                 <input class="ep_radio" type="radio" name="1003488_dan" value="1">
                                 <b>A.</b>
                                 <p><span style="font-family: 宋体;">毕业生没有落实新接收单位或人事代理机构，其档案和户口改派至原来的学院资料存放处</span></p>                                </label></li>
                                <li><label>
                                    <input class="ep_radio" type="radio" name="1003488_dan" value="2">
                                    <b>B.</b>
                                    <p><span style="font-family: 宋体;">毕业生没有落实新接收单位或人事代理机构，其档案和户口改派至家庭户口所在地</span></p>                                </label></li>
                                <li><label>
                                    <input class="ep_radio" type="radio" name="1003488_dan" value="3">
                                 <b>C.</b>
                                 <p><span style="font-family: 宋体;">毕业生没有落实新接收单位或人事代理机构，其档案和户口改派至毕业生生源所在地毕业生就业主管部门</span></p>                                </label></li>
                                <li><label>
                                    <input class="ep_radio" type="radio" name="1003488_dan" value="4">
                                    <b>D.</b>
                                    <p><span style="font-family: 宋体;">毕业生没有落实新接收单位或人事代理机构，其档案和户口改派至辅导员存放资料处</span></p>                                </label></li>
                            </ul>
                        </div> <!-- 50个这种单选，如何使用js和dom控制这个表单，让脚本自动答题，（不保证正确性） -->
                        <!-- 单选 end-->
                                           </div>
   </form>