立功的英文：
achieve distinction
gain distinction
perform exploits
supererogation

参考例句：

The sentence shall be reduced if any of the following meritorious services are performed
有下列重大立功表现之一的，应当减刑

Those who performed major meritorious service may be given a mitigated punishment or may be exempted from punishment.
有重大立功表现的，可以减轻或者免除处罚。

achieve是什么意思：
v.
1.[T]（凭长期努力）达到（某目标、地位、标准）
2.[T]完成
3.[I]成功

Achievement goals theory is the advance subject of achievement motivation.
成就目标理论是成就动机研究的前沿课题。是目标设置研究的延伸。

This achievement cannot be bettered.
这一成就好得不能再好了。

He has achieved the aim.
他已达到目的了。

distinction是什么意思：
n. 区别；卓越；特质；荣誉

acquired distinctiveness
经（使用或其它方法）取得的独特性

There is a distinct smell of oranges in this room!
这个房间里有明显的桔子味！

radically distinctive and without equal.
非常独特、没有相等的事物。

gain是什么意思：
v. 获得；获利；增加；走快；到达
n. 增加；利润；收获

No pains, no gains.
不劳则无获。

This ticket will gain you admission [will gain admission for you].
这张票将使你得以入场。

Its gain is the product of the gains of its constituent branches.
它的增益等于它含有的分支的增益的积。