at the cost of

We must cherish experience acquired at the cost of blood.

我们必须珍惜用鲜血换来经验。

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

那只可怜小狐狸逃出了陷阱, 却失去了一条腿。

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

他救这小孩于淹死却牺牲了自己生命。