If you can't find a file on your computer or you accidently modified or deleted a file, you can restore it from a backup (if you're using Windows backup) or you can try to restore it from a previous version.Previous versions are copies of files and folders that Windows automatically saves as part of a restore point.

Examples. Following are examples of some common nested IF(AND()), IF(OR()) and IF(NOT()) statements in Excel. The AND and OR functions can support up to 255 individual conditions, but it’s not good practice to use more than a few because complex, nested formulas can get very difficult to build, test and maintain.

從 [概觀] 頁面選取 [Office 應用程式]，然後在該頁面上尋找您要安裝的 Microsoft 365 產品，然後選取 [ 安裝]。 若要以不同的語言安裝 Microsoft 365 ，或安裝 64 位版本，請使用下拉式清單來尋找更多選項。選擇您想要的語言和位元版本，然後選取安裝。

获取 Windows 操作系统的官方支持和帮助信息，以及如何使用 Windows 的指南。

Safe mode starts Windows in a basic state, using a limited set of files and drivers. If a problem doesn't happen in safe mode, this means that default settings and basic device drivers aren't causing the issue.

Select Add a keyboard and choose the keyboard you want to add. If you don't see the keyboard you want, you may have to add a new language to get additional options. If this is the case, go on to step 4.

In the list next to Personalize your background, select Picture, Solid color, Slideshow, or Windows Spotlight (to see a new image from around the world every day).

In quick settings: To find the quick setting for Bluetooth, select the Network, Sound, or Battery icons ( ) next to the time and date on the right side of your taskbar.Select Bluetooth to turn it on. If it's turned on without any Bluetooth devices connected, it might appear as Not connected . If you don't see Bluetooth in quick settings, you might need to add it.

Select Add a printer or scanner.. Wait for it to find nearby scanners, then choose the one you want to use and select Add device.

完全关闭电脑 若要关闭，请选择" 开始"， 然后选择" 电源 > 关闭"。 睡眠 睡眠使用非常少的电源，你的电脑启动速度更快，你可以立即返回到你离开的地方。 不必担心因电池耗尽而丢失工作，因为如果电量不足，Windows自动保存所有工作并关闭电脑。