These are so rare that we have to limit distribution of one unit per customer per three years.

- 这种情况非常罕见，因此我们必须限制每三年向每个客户分配一个单位。

Without human workers, power plants are prone to  failures and may shut down in a matter of days, limiting the distribution of other resources like  water and natural gas.

如果没有人类工人， 发电厂很容易出现故障， 并可能在几天内关闭，从而限制了水和天然气等其他资源的分配。