问题如下：
Under the revaluation model, company M sold some of its long-lived assets last year, the gain or loss of company M may be recorded as:
选项：
A. sales proceeds less carrying amount.
B. sales proceeds less historical cost net of accumulated depreciation.
C. sales proceeds less carrying amount adjusted for impairment.
解释：
A is correct. When it comes to the sale of long-lived assets measured by revaluation model, the gain or loss is calculated by sales proceeds less the carrying amount of the asset at the time of sale. Under the cost model, if there is no impairment loss, the carrying amount is the same as historical cost net of accumulated depreciation.
答案也没有解释为什么这样计算，这是个知识点吗？课件里面没有涉及到吧
