She knew it would be difficult to undo the damage that had been done.

她知道难以挽回已造成的损失。

《柯林斯英汉双解大词典》

Realize that a letter can't undo the damage.

l意识到单单一封信无法弥补伤害。

youdao

So maybe during the day, I can rush around and undo the damage.

这样白天我就可以挽回些损失。

youdao

Some residents fear no payment can undo the damage.

VOA: standard.2010.06.01

Our real economy is growing again, but too slowly to undo the damage of 2008-2009.

FORBES: Magazine Article

It's going to take time to undo the damage of years of carve-outs and loopholes.

WHITEHOUSE: Real Tax Cuts Making a Real Difference

Since then, the Republican Party has tried every sort of gimmick to undo the damage but to no avail.

FORBES: 5 Ways Romney Could Have Won the Election With Data, Social and Mobile