原始信息来自：http://iphonetipsandtricks.lookitupforme.com/things-you-can-do-on-an-ipad-with-an-external-keyboard/
更详细的可参考：http://ipad.appstorm.net/how-to/lifestyle/is-an-external-keyboard-really-worth-it/
Thing you can do only with an external keyboard.
- You can cut, copy, and paste quickly with Command + X, C, and V.
- You can select text instantly using Shift + the cursor control keys.
- You can go to the beginning or end of the line with Command + left or right arrow keys.
- You can do the same thing to get to the top or bottom of a document using the up and down arrow keys. In fact, you can use the cursor control keys just a you would on a normal computer. Including Shift, Command, and Option combinations.
- You can adjust the brightness of the screen with the F2 and F3 keys – no need to go into Settings.
- You can easily control the volume and mute the iPad using the volume control keys on the keypad.
- You can control the iPod (play, pause, skip, reverse, volume) directly from the physical keyboard without leaving the app you are working/playing with right now.
Thing you can do only with the software keyboard.
Ok. That’s all good. But what do you do when you want to dictate. There is no “Siri” or microphone key on the physical keyboard. Simple, just press the “Eject” key and the physical keyboard will be “ejected” and the soft keyboard will slide in. You can now touch the microphone and dictate away. When you want to go back to the physical keyboard, just touch the Eject key on the physical keyboard and the software keyboard will slide out of the screen.