汗马功劳的英文：
[Literal Meaning]
sweat/horse/contribution
one's contributions as a soldier who rides a sweating horse

[解释]
古代指在战场上建立战功。现指辛勤工作做出的贡献。

[Explanation]
one's contributions in work

[例子]
在美国的华工为修筑铁路立下了汗马功劳，却受到了不公平的待遇。

[Example]
The Chinese labors in the US had made their contributions in building railway but were treated unfairly.