问题如下：
Under LIFO, XYZ company reported COGS of $500,000, and ending inventory of $600,000 in 2017, and in the footnotes record LIFO reserve increased $10,000, if XYZ company change accounting method, LIFO change to FIFO method, its cost of goods sold was:
选项：
A.$510,000
B.$500,000
C.$490,000
解释：
C is correct.
FIFO COGS = LIFO COGS –△LIFO reserve
=500,000-10,000=490,000.
虽然答案是选对了，但是in the footnotes record LIFO reserve 中的LIFO reserve 不是应该看成是一个时间点报表上的值？ 当期先进先出法储备是不是应该取average ? 如果去找到这个改变量?
