我以前对这个问题也没搞清楚，后来翻了下原版书，这是我的笔记，希望对你有用。
在GAAP下，Inventory减值是增加COGS的，并且减值不允许回转。【 Any write-down reduces the value of the inventory, and the loss in value (expense) is generally reflected in the income statement in cost of goods sold.
(Institute 382)
Institute, CFA. Level I 2013 Volume 3 Financial Reporting and Analysis. John Wiley & Sons P&T, 7/3/2012. VitalBook file.
】
而在IFRS下，Inventory减值是计入expense的，回转时减少COGS。【The amount of any reversal of any write-down of inventory arising from an increase in net realisable value is recognised as a reduction in cost of sales (a reduction in the amount of inventories recognised as an expense).
(Institute 382)
Institute, CFA. Level I 2013 Volume 3 Financial Reporting and Analysis. John Wiley & Sons P&T, 7/3/2012. VitalBook file.】
如果是减值后，在IFRS下，公司自身前后的gross profit的比较的话，因为减值相关金额计入expense的增加，而对COGS不产生影响，所以gross profit是相同的；因为在GAAP中，减值是计COGS增加，从而导致gross profit减少。

非常感谢你！！！

：）

谢谢

非常感谢！很清晰的解答！

感谢感谢！