为虎作伥的英文：
[Literal Meaning]
for/tiger/to be/Chang
to be the Chang of the tiger

[解释]
充当恶人的帮凶。

[Explanation]
to be the aid of the evil

[例子]
他干了那么多坏事，如果你去法庭上为他开脱，就是为虎作伥。

[Example]
He did a lot of evil. If you exonerate for him in the court, you will be the aid of the evil.

[英文等价词]
to hold a candle to the devil
play the jackal to the tiger

To act as guide to a tiger
为虎作伥

Hold a candle for the devil
为虎作伥

accomplice;act as a cat's-paw;Act as a jackal to tiger;lackey
为虎作伥

His seven councilors…abet him in the outrage
他的七位枢密大臣…为虎作伥。