one to fall back on

Know at least two or three languages, so if one dies off, you have another one to fall back on while you train for a new technology.

至少了解两到三种 语言，所以，如果某种语言过时了，你在学习新技术的时候还可以依靠另一种语言。

Allowing one customer to dictate my hours was the worst mistake I ever made as when that contract was over I had nothing to fall back on.

让一个客户对我指手画脚是我曾犯过的最大的错误，因为当这份合同结束时我再也没有其他的客户了。

In this way if one crop gets diseased, or one harvest succumbs to drought, or one hillside is flooded, they have alternatives to fall back on.

凭借这种方法，如果作物生了病，或者收成受到干旱的影响，或者遭遇山洪，他们都有替代的方法可供依靠。