了解iCloud照片库的工作原理。 打开设置。 点击“iCloud”，然后选择“照片”。 选择“优化iPad储存空间”。 打开照片下载它的全分辨版本。

I'm interested in that, but I only have a few mins. Can you give me at most the first 500 characters of a detailed explanation in English about that?
With the iOS 8 update, Apple introduced the iCloud Photo Library beta. This program allows you to automatically upload and store all of your photos on your iCloud Drive, making them instantly available on any of your devices. What this means is that every device that has iCloud Photo Library enabled will download and store a copy of each photo onto the device's local storage. To save space on your iPad when using the iCloud Photo Library, you can opt to only store smaller versions of the image o