How did these people come to gang up?

他们这帮人怎么勾上的？

《新英汉大辞典》

There were innumerable thieves, a gang of roughs tried several times to break things up, and police were everywhere.

那里的小偷多得数不清，有一帮暴徒几次试图破坏秩序，到处都是警察。

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The gang worked for up to ten hours with acetylene torches to open the vault.

这帮强盗为了打开金库，用乙炔吹管干了长达10个小时。

《柯林斯英汉双解大词典》

There he joined forces with European governments in an attempt to gang up on Israel at the G8 meeting.

CENTERFORSECURITYPOLICY: Where Obama is leading Israel

And two other middle-of-the-road parties, the Liberals and the Christian Democrats, both sound as unkeen as Mr Daleus is to gang up with Mr Persson.

ECONOMIST: Sweden

In this fight, both Republicans and Democrats are on the same side, joining forces, as they have for decades, to gang up on our kids.

FORBES: Another Victory in the War on Our Children