Before revision: If an individual learned how to ski in the 70s, when they had straight skis, and he or she hasn’t skied for years, they would have to relearn how to ski with the more modern rounded downhill skills.
After revision: If someone learned how to ski in the 70s, when they had straight skis, and he or she hasn’t skied for years, they would have to relearn how to ski with the more modern rounded downhill skills.