两位议员同意互相支持，通过交换条件来推动各自的提案。

The two legislators agreed to ___log-roll to advance each other's proposals.

在森林运动会上，参赛者需要在滚动的原木上行走以测试他们的平衡能力。

At the forest games, competitors had to ___log-roll on moving logs to test their balance.