After the 1900-2000 major central zone detaches, it quickly rebounds to touch the original central zone, then detaches again, with the bearish momentum weakening (using range trading, two green bars getting smaller to judge). When a buy position appears at this time, the market completely reverses. This also indicates that the major central zone has significant gravitational pull. This time, the second bottoming and rebound are also validated. As long as a new central zone is not formed again at 2060 but instead breaks through 2100 to form a new central zone, a new bull market can begin.