at the cost of

We must cherish experience acquired at the cost of blood.

我们必须珍惜用鲜血经验。

He rescued the boy from drowning at the cost of his own life.

他救这小孩免于淹死却牺牲了己生命。

The poor fox escaped from the trap at the cost of a leg.

那只可怜小狐逃出了陷阱, 却失去了一条腿。