Notes: 1. When running the mobile phone emulator, it fails to run: it prompts that the mobile phone emulator is already running, and it will not work when it is closed and reopened.
AVD Pixel_3a_XL_API_28 is already running.
If that is not the case, delete the files at
H:\Users\ASUS\.android\avd/Pixel_3a_XL_API_28.avd/*.lock
and try again. 
依然会提示： The selected AVD is currently running in the Emulator. Please exit the emulator instance and try wiping again.
2. Solution:
(1) Find the location of the avd file and open it (C:\Users\ASUS\.android\avd\Pixel_3a_XL_API_28.avd)
(2) Delete this folder
Note: If there is a prompt that this folder cannot be deleted and has been opened in another program, it will not appear after closing the android program and deleting it.
3. Results:
