natural restriction

例句：

1. 1. The government has imposed a natural restriction on the number of cars that can be registered in the city.
   政府已经对城市内汽车注册数量施加了自然限制。
2. 2. The scientist discovered a natural restriction in the process that could be overcome with further research.
   科学家发现在过程中存在一个自然限制，通过进一步研究可以克服。
3. 3. The team was restricted by the natural constraints of their environment.
   团队受到其环境的自然限制。