Use voting buttons in messages - Microsoft Support
If you encrypt an Outlook message that contains voting buttons, message recipients won't be able to see them. That feature isn't supported at this time. Create an email message or reply to or forward a message that you received. On the Options tab, in the Tracking group, click Use Voting Buttons.
Applies To:
Outlook for Microsoft 365, Outlook 2021, Outlook 2019, Outlook 2016, Outlook 2013
PowerPoint 支持的视频和音频文件格式 - Microsoft 支持
建议的格式. 视频 ：.mp4 使用 H.264 视频和 AAC 音频编码的文件. 音频 ：.m4a使用 AAC 音频编码的文件. 这些名称和格式听起来可能很复杂，但你可以轻松地转换为并使用这些格式，而无需知道除名称以外的任何内容。.
Applies To:
PowerPoint for Microsoft 365, PowerPoint for Microsoft 365 for Mac, PowerPoint 2021, PowerPoint 2021 for Mac, PowerPoint 2019, PowerPoint 2019 for Mac, PowerPoint 2016, PowerPoint for iPad, PowerPoint for iPhone, PowerPoint for Android tablets, PowerPoint for Android phones, PowerPoint for Windows Phone 10, PowerPoint Mobile
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