Do you remember playing the "bean bag toss" game when you were a kid? We only saw the result of tossing the bean bag! But he didn’t know the angle and strength of the throw, and he didn’t know whose back the bean bag was placed, and he sat there in confusion! Just like everyone discussing one country, two systems, everyone has their own opinions and positions, but have you ever thought that there is actually a scientific method and data analysis behind it? Let’s learn about this index together, and no longer just stay at superficial arguments and opinions!