Use the System File Checker tool to repair missing or corrupted system ...
Describes how to use the System File Checker tool to troubleshoot missing or corrupted system files in Windows 8.1, Windows 8, Windows 7 or Windows Vista.
Manage your Microsoft 365 subscription or Office product
You can manage all of your Microsoft subscriptions in your Microsoft account dashboard. Select each subscription to change when and how you pay, or to see order history & receipts.
Applies To:
Excel for Microsoft 365, Word for Microsoft 365, Outlook for Microsoft 365, PowerPoint for Microsoft 365, Access for Microsoft 365, OneNote for Microsoft 365, Publisher for Microsoft 365, Visio Plan 2, Excel for Microsoft 365 for Mac, Word for Microsoft 365 for Mac, Outlook for Microsoft 365 for Mac, PowerPoint for Microsoft 365 for Mac, OneNote for Microsoft 365 for Mac, Word for the web, OneNote for the web, PowerPoint for the web, Excel 2021, Word 2021, Outlook 2021, Access 2021, Project Professional 2021, Project Standard 2021, Publisher 2021, Visio Professional 2021, Visio Standard 2021, Office 2021, OneNote 2021, Excel 2021 for Mac, Word 2021 for Mac, Outlook 2021 for Mac, OneNote 2021 for Mac, Office 2021 for Mac, Excel 2019, Word 2019, Outlook 2019, PowerPoint 2019, Access 2019, Project Professional 2019, Project Standard 2019, Publisher 2019, Visio Professional 2019, Visio Standard 2019, Office 2019, Excel 2019 for Mac, Word 2019 for Mac, Outlook 2019 for Mac, PowerPoint 2019 for Mac, OneNote 2019 for Mac, Office 2019 for Mac, Excel 2016, Word 2016, Outlook 2016, PowerPoint 2016, Access 2016, OneNote 2016, Project Professional 2016, Project Standard 2016, Publisher 2016, Visio Professional 2016, Visio Standard 2016, Office 2016, Microsoft 365 admin, Outlook on the web, Word Web App, Microsoft account dashboard, New Outlook for Windows
Download and install apps - Microsoft Support
Learn how to download and install apps you need from your Microsoft 365 business subscription.
Upgrade Windows Home to Windows Pro - Microsoft Support
Learn how to upgrade from Windows 10 Home to Windows 10 Pro or Windows 11 Home to Windows 11 Pro, including how to use a valid product key or the Microsoft Store.
Install and use a scanner in Windows 10 - Microsoft Support
Learn how to install a scanner and use it to scan pictures and documents in Windows 10.
Free up drive space in Windows - Microsoft Support
Learn how you can free up drive space in Windows. Keep your PC running smoothly and up to date by increasing the disk space.
Use voice typing to talk instead of type on your PC
Use dictation to convert spoken words into text anywhere on your PC with Windows.
Find your Windows product key - Microsoft Support
Learn how to find a Windows product key for activation, and when you'll use a digital license instead.
Applies To:
Microsoft account dashboard
在 Excel 中将 IF 与 AND、OR 和 NOT 函数配合使用 - Microsoft 支持
下面是 Excel 中一些常见的嵌套 IF (AND ) 、IF (OR ) 和 IF (NOT ) 语句的示例。 AND 和 OR 函数最多可支持 255 个单独条件，但并不建议使用多个条件，因为构建、测试和维护复杂的嵌套公式是非常难的。
Applies To:
Excel for Microsoft 365, Excel for Microsoft 365 for Mac, Excel for the web, Excel 2021, Excel 2021 for Mac, Excel 2019, Excel 2019 for Mac, Excel 2016, Excel Web App, Excel for Windows Phone 10
Manage photos and videos with Microsoft Photos app
Learn how the Photos app for Windows lets you view photos and videos from your PC alongside those from OneDrive, and keeps them organized by date, album, or folder.