My Chinese writing is not good and I am writing in English to address your problem because CFA is also an English exam.

Under the LIFO principle and in times of stable and inflation.  The last batch of inventory with higher purchase price and be transferred to inventory as COGS which will have a higher COGS than under FIFO.  If you can grasp this principle.  the American like this LIFO as their accounting policy because higher cost will mean they are paying less tax under inflation period.