拥有一些可以依靠的积蓄是明智的。

It's wise to have some savings to ___fall ___back ___on.

紧急情况下，你可以依靠我的邻居。

In an emergency, you can ___fall ___back ___on my neighbors.

当新软件失效时，团队不得不依靠他们那些老旧但可靠的方法。

When the new software failed, the team had to ___fall ___back ___on their old, reliable methods.