肝血管瘤3例动脉期瘤内无强化，门静脉期呈向心性填充增强，持续数分钟后消退； 余4例良性病灶变化不典型。

The 3 cases of haemangioma were enhanced centripetally in portal phase and washed out after several minutes without arterial enhancement and the other 4 benign cases without typical enhancement.

youdao

And, in fact, once you teach an animal something, if you stop doing the teaching the response goes away and this is known as extinction.

事实上，条件反射形成以后，如果得不到强化,条件反应就会逐渐消失,这就是消退。

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wouldn't there be extinction after a while?

在强化消失后是否也会发生消退？

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