此功能不适用于 AMPHTML 广告。
在加载广告的剩余部分时（尤其是当广告比较大时），展示一张图片通常会非常有用。
1. 设置“正在加载”图片
将 ID 为“loading”的 div 添加到 HTML 中：
<body style="visibility: hidden;">
<div id="loading" class="loading-image">
Loading...
</div>
<gwd-google-ad id="gwd-ad" polite-load="">
...
</gwd-google-ad>
</body>2. 停止展示“正在加载”图片
要隐藏或移除“正在加载”图片，您只需向 handleAdInitialized 函数添加代码即可。系统会在广告初始化之后调用此方法。如果您已启用礼让加载，系统则会在分派 PAGE_LOADED（启动器）事件之后调用此方法。
隐藏“正在加载”图片
以下突出显示的代码将会隐藏“正在加载”图片：
/**
* Handles the event that is dispatched after the Ad has been
* initialized and before the default page of the Ad is shown.
*/
function handleAdInitialized(event) {
// This marks the end of the polite load phase of the Ad. If a
// loading image was shown to the user, this is a good place to
// remove it.
document.getElementById('loading').style.display = 'none';
}移除“正在加载”图片
以下突出显示的代码将会移除“正在加载”图片：
/**
* Handles the event that is dispatched after the Ad has been
* initialized and before the default page of the Ad is shown.
*/
function handleAdInitialized(event) {
// This marks the end of the polite load phase of the Ad. If a
// loading image was shown to the user, this is a good place to
// remove it.
document.body.removeChild(document.getElementById('loading'));
}