求翻译：对不同投资方案进行经济比较时，不仅要考虑支出和收入的数额，还必须考虑每笔现金流量发生的时间，以某一个相同的时点为基准，把不同时点上的支出和收入折算到同一个时点上，才能得出正确的结论。是什么意思？

Economic comparison of different investment programs, not only to take into account the amount of expenditure and income, you must also consider the time of each cash flow, as the benchmark to a certain point in time, at different points on the expenditure and income are translated to the same point

On the different investment program for economic, not only to consider the expenditure and income level, you must also take into account each time by the cash flow to the same point in time, and to the point is not the same on the conversion to revenue and expenditure with a point in time, to draw t

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Economic comparison of different investment programmes, not only taking into account the level of expenditure and income, must also consider the time of each cash flow occurs, one to the same point as the base, conversion and revenue to spend on different points on the same point, in order to draw t

Carries on the economical comparison when to the different investment plan, not only must consider the income and expenditure the amount, but also must consider each cash current capacity occurs the time, take some same point in time as a datum, difference when lights the income and expenditure conv