顺水推舟（順水推舟）　

◎ 顺水推舟，顺水推船 shùnshuǐ-tuīzhōu,shùnshuǐ-tuīchuán

[push the boat along with the current—make use of an opportunity to gain one’s end] 比喻顺应形势行事

天地也!做得个怕硬欺软,却原来也这般顺水推船!——元· 关汉卿《窦娥冤》