This ball is used in the choreography of our university, and people dance in it.

Three people were practicing dancing in the ball that day, and one of them was in charge of looking after it, but the person in charge of looking after it went out to buy milk tea for 40 minutes and completely forgot about the three people in the ball.

It was also Sunday, and there were few people, and no one came to the dance studio.

When he came back, he saw that two of the three people were already unconscious in the ball. One patted the ball wall for help and quickly cut the ball with a knife to save them. Fortunately, the coma is not serious. If you are 10 minutes late, three people will die.

According to them, after about 20 minutes in the ball, I feel short of breath, and it doesn't help to think about it. When they wanted to come out by themselves, they found that the zipper could not be unzipped at all. After waiting for a few minutes, no one came back, and they were a little panicked. You can't break the ball wall by pulling hard. You didn't bring anything when you scored, and you can't cut it if you want. Tear hard with your hands, but you can't break the ball wall with your feet. Two of them struggled for a while and then collapsed. The other is that the ball will leak when it meets something sharp, and the ball will gradually deflate, so the oxygen coming in through the small hole will stay awake. But it's still wrapped in a ball, and she can't tear the material open. She can't bite it with her teeth, can't come out, can't walk, and can only beat it for help.

So I also want to know how to save myself.