Dual-system boot problems during installation of my windows 8 consumer Preview

I installed Windows 8 on a CD.
The CD installation process is very simple and similar to Windows 7 (I feel faster than Windows 7)
I encountered some problems during the installation process.
1. Write down the serial number (officially provided by Microsoft) In case that the serial number is unknown after installation.
2. After Windows 7 is installed, the system boot for Windows 7 is lost.
Solution: put the boot disk of Windows 7 into the optical drive and go to the installation page. Find the boot and repair options and fix the issue. At this time, when you are about to enter Windows 8, there will be an option for you to choose to enter Windows 7 or Windows 8
If you select to enter Windows 7, it will restart to enter Windows 7. Obviously, this will slow down when we enter Windows 7. To speed up, right-click the computer after entering Windows 7 → advanced system settings → advanced → start and fault recovery (SET) → select the system you want to start first as the default startup