SUMIFS function - Microsoft Support
How to use the SUMIFS function in Excel, one of Excel’s math and trig functions, to add arguments that meet multiple criteria.
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
下载Microsoft Authenticator - Microsoft 支持
使用双重验证时，Microsoft Authenticator 应用可帮助你登录帐户。
UNIQUE function - Microsoft Support
Learn about the UNIQUE function, which returns a list of unique values in a list or range. UNIQUE is in a class of functions called dynamic arrays.
Applies To:
Excel for Microsoft 365, Excel for Microsoft 365 for Mac, Excel for the web, Excel 2021, Excel 2021 for Mac, Excel for iPad, Excel for iPhone, Excel for Android tablets, Excel for Android phones
INDEX function - Microsoft Support
How to use the INDEX function in Excel to return a value or reference to a value within a table or range.
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
Download and install or reinstall Microsoft 365 or Office 2021 on a PC ...
Learn how to install, reinstall, or activate Microsoft 365 or Office 2019 on a PC or Mac.
Applies To:
Office 2021, Office 2021 for Mac, Office 2019, Office 2019 for Mac, Microsoft 365 for home, Office for business, Office 365 Small Business, Microsoft 365 admin, Office 365 operated by 21Vianet, Office 365 operated by 21Vianet - Admin, Microsoft 365 for Mac, Office 365 Germany - Enterprise, Office 365 Germany - Enterprise admin
Send feedback to Microsoft with the Feedback Hub app
Learn how to use Feedback Hub to report problems or send suggestions to Microsoft.
CONCATENATE function - Microsoft Support
Learn how to concatenate text strings in Excel using the CONCATENATE function. Our step-by-step guide makes it easy to join two or more text strings into one.
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
Where to enter your Office product key - Microsoft Support
If your purchase of Office or Microsoft 365 came with a product key, you enter your product key on one of the websites listed below for your product.
Applies To:
Office 2021, Office 2021 for Mac, Office 2019, Office 2019 for Mac, Office 2016, Microsoft 365 for home, Office for business
Introduction to Outlook Data Files (.pst and .ost)
Outlook Data Files contain your email messages, calendar, tasks, and other items on your computer.
Applies To:
Outlook for Microsoft 365, Outlook 2021, Outlook 2019, Outlook 2016
Use add-ins in Outlook - Microsoft Support
The dialog that appears varies depending on whether you had the Add Apps or Get Add-ins option available to you. If you selected Add Apps, the Apps dialog appears. If you selected Get Add-ins, the Add-Ins for Outlook dialog appears. Search for the add-in you want from the available list.
Applies To:
Outlook for Microsoft 365, Outlook 2021, Outlook 2019, Outlook 2016, Outlook on the web, New Outlook for Windows, Outlook Web App