串通: (暗中勾结, 使彼此语言行动互相配合) gang up; collaborate; collude with; be in collusion with; work hand in glove with; conspire with sb. for illegal acts; conspire with:被告和原告串通。the defendant colluded with
串通作弊: league together for some evil end; be in collusion over corrupt practices; conspire with sb. for illegal acts; conspire to cheat
勾结: collude with; play footsie (with); in league with; be hand and glove with; collaborate with; gang up with 短语和例子与 ...相勾结 in collusion with...; 勾结成一伙来对付某人 gang up against [on] sb.; 既勾结又争夺 at