[译] 这样做我们可以为国家节省一大笔钱。
[误] By doing that we could spare a large sum of money for the state.

[正] By doing that we could save a large sum of money for the state.
[注] save 表示“节省”、“储蓄”，spare 表示“抽出（时间、精力）”等，请注意区别。如：I'm afraid we have little time to spare these few days. 恐怕这几天我们抽不出什么时间来。