it is difficult to achieve anything alone or without the support and cooperation of others

单打独斗很难成事，毕竟一个巴掌拍不响，我们需要团队的支持。

it takes two persons to start a dispute or be involved in a situation; both parties share responsibility

他们两个闹矛盾，一个巴掌拍不响，肯定双方都有错。