They have been alerted to the possibility of further price rises.

他们己意识到价格可能继续上涨。

牛津字典上写的用法是alert sb to sth 使认识到，使意识到。

我想问他为什么要加been。是因为alert sb to sth=sb be alerted to sth吗？

—— alert sb to sth 使认识到，使意识到：此结构一般现在时的被动式是：Sb.is alerted to sth.

They are alerted to sth. 改为现在完成时，便是：

They have been alerted to the possibility of further price rises.