换防的英文：
relieve

relieve是什么意思：
v. 缓和，减轻；换…的班；调剂；救济；使宽慰；解除职务

The corporal will relieve the sentry in an hour.
下士一小时后接替卫兵。

I can not relieve the oppression of the heart.
我难以消除心头的压抑。

We are all relieved to be back home.
回到家里我们都感到安心了。

He devoted himself to relieving the distressed.
他献身救助不幸者。

Money relieved her of material difficulties.
金钱免除了她的经济困难。