定位元素没有问题，但是执行脚本时候，循环第二遍时候，就报错is not clickable at point (1214, 124). Other element would receive the click。
具体错误：selenium.common.exceptions.WebDriverException: Message: unknown error: Element <img src="../images/tianjia_btn_pre.png" id="add" ng-click="showAddUserDialog()" ng-mouseover="changeImage('add','../images/tianjia_btn.png')" ng-mouseout="changeImage('add','../images/tianjia_btn_pre.png')"> is not clickable at point (1214, 124). Other element would receive the click: <div class="modal fade in" role="dialog" id="myModal" aria-hidden="true" style="display: block; padding-right: 17px;">...</div>
通过错误提示，应该是在循环第二遍点击添加按钮时，被其他元素接受了鼠标单击，也就是被其他元素遮挡，所以在循环点击之前，稍作sleep休眠即可。