Why did coins appear 70 years ago?

1. Looking for the helmet key: Yang Guang looked around for the helmet key in the play and finally found it in a hidden place.

2. Unlocking the helmet: After finding the key, Yang Guang inserted the key into the keyhole of the helmet and turned the key counterclockwise to successfully unlock the helmet.

3. Take off the helmet: After undoing the helmet, Yang Guang took it off his head.