It may be that the online registration system for senior high school entrance examination has not been opened or the registration time has passed. Under normal circumstances, the online registration system for senior high school entrance examination has a time limit. Therefore, if it has not been opened or the registration time has passed, it is impossible to log in.
The senior high school entrance examination generally refers to the junior high school academic level examination. Junior high school graduation examination, referred to as "senior high school entrance examination", is an examination to test whether junior high school graduates reach the junior high school graduation level. It is a necessary condition for the issuance of junior high school diplomas.