to use something, especially a form of financial support, when other things have failed
借助于；依赖，依靠

例句：

When the business failed, we had to fall back on our savings. 公司倒闭后，我们只得靠积蓄度日。

If I lose my job, I’ll have nothing to fall back on. 我要是丢了工作，就什么指望都没有了。

The company is force to fall back on its cash reserve. 这个公司被迫动用它自己的现金储备。

Doctors sometimes fall back on old cures. 有时医生们求助于老的疗法。

She always has her teaching experience to fall back on. 她总还有教学经验可以依赖。

Don’t fall back on others but do the job yourself. 别依赖别人，你自己干。

Fall back on old friends in time of need. 在需要时求助于老朋友们。