How to tie knots for outdoor sports?

Haha, brothers, please remember to have a backup when you are playing dangerous sports such as high-altitude rappelling outdoors. Don’t just tie a figure eight knot. That is irresponsible for life. I I saw that many outdoor clubs have two backups, or even three. Safety comes first. The figure eight knot is actually very simple. First tie a single figure eight, then go back to the original route, and the figure eight knot is fixed on a book or On the relay point. I haven’t played it in years, but I still played it a lot when I was in Scout. I went to some outdoor forums and saw that there are many ways to tie knots. If you like it, study it. I wish you a happy time.