change a for b

基本解释

B: Why don’t you go there by boat for a change?
你为什么不换一种方式，坐船去呢？
B: Well, I think I'll take the bus this time just for a change.
哦，我想这次我还是换一下走法，乘公车。
Her mother, Deborah Konyk, would prefer that Nadia, who gets A’s and B’s at school, read books for a change.
妈妈Deborah Konyk希望Nadia可以改变现在的生活状态，在学校拿到好成绩，读些书。

More recent data is weighed more heavily. (This was a recent change.) If you had picture A, B, and C up for one year, and then took them down in favor of pictures X, Y, and Z, then within just a couple weeks your score would be determined mostly by X, Y, and Z.
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Usually the potential for change is building for a long time, but then there is some environmental shift (visually depicted as B, below.) The old is made obsolete while the new grows aggressively.
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