Remark:
I haven't tried this method, I will download the latest Lao Mao Tao and try it later.
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The following are the setting steps:
1. Restart the computer first, and press the "F1" key on the notebook keyboard to enter the notebook's BIOS setting interface.
2. After entering the BIOS setting interface, press the "→" key on the keyboard to move the menu to the "Restart" item, press the "↓" key on the keyboard to select the "OS Optimized Defaults" option, and press the "Enter" key to open In the setting menu of this option, press the "↑" button on the keyboard to change the default "Enabled" of the option to "Disabled", and then press the "Enter" button to confirm. Press the "↑" key on the keyboard to select the "Load Setup Defaults" option, press the Enter key to start the restore BIOS default function window, and directly press the "Enter" key on the laptop keyboard to start the BIOS restore default function in this window. Then press the "F10" key on the laptop keyboard to start the BIOS save settings window, in this window directly press the "Enter" key on the laptop keyboard to start the BIOS save settings and restart the computer function. (As shown below) 
3. When the computer restarts to the "Lenovo" LOGO screen, press the "F1" key on the laptop keyboard to enter the laptop's BIOS setting interface, and press the "→" key on the keyboard to move the menu to "Startup" item, press the "↓" button on the keyboard to select the "UEFI/Legacy Boot" option, press the "Enter" button to open the setting menu of this option, press the "↓" button on the keyboard and set the option to "Both" by default "Modify to "Legacy Only" and press "Enter" to confirm. Then press the "F10" key on the laptop keyboard to start the BIOS save settings window, in this window directly press the "Enter" key on the laptop keyboard to start the BIOS to save the settings and start the computer function honestly. (As shown in the figure below) 
4. When the computer restarts to the "Lenovo" LOGO screen, press the "F12" key on the notebook keyboard to enter the notebook's boot setting interface. Select U disk to start! ! 
Finally, the most important point is that the U disk boot tool should use the latest old Mao Tao or the general PE WIN8 version! ! Otherwise, the old version will not recognize the U disk after entering PE,
so the system is installed and available for personal testing.