问题如下：
4. A switch from straight-line to accelerated depreciation would:
选项：
A.increase the NPV and decrease the first year operating income after taxes.
B.increase the first year operating income after taxes and decrease the NPV.
C.increase both the NPV and first year operating income after taxes.
解释：
A is correct.
Accelerated depreciation shifts depreciation expense toward the earlier years so that first-year operating income after taxes will be lower. However, because depreciation is a noncash expense, it must be added back to operating income after taxes in order to obtain after-tax operating cash flow. This process shifts cash flows from later years to earlier years, increasing the NPV.
老师，判断对于OCF的影响，是否应从OCF=(S-C)*(1-T) + DEP*tax 出发，而不是(S-C-D)*(1-t)+DEP？
