threshold constraint

例句：

1. 1. The new policy has raised the threshold for environmental protection.
   新的政策提高了环保的门槛。
2. 2. The company's profits have reached a threshold that can no longer be surpassed.
   公司的盈利已经达到了一个无法超越的门槛。
3. 3. The research team has identified a threshold at which the disease begins to spread.
   研究团队已经确定了疾病开始传播的门槛。