There is no need to register, and it is free. You can also find other versions of teaching materials. The only drawback is that the downloaded documents are all compressed, the titles are all numbers, and there is no resolution ... but it is still very good.

The Hong Kong-China Mathematics Network and the Middle School Subject Network are also good, and Sina Aiwen can also find many things that don't need integral, which is still good ~ ~

You can also post lesson plans on Baidu ~ ~ Baidu is so powerful that there are always many good things in the library. If you look through it more, you will find something that costs nothing and doesn't score points! ~~~~~