[单选题]You will have no reason to think about the merely statistical fact of the number of years you have already lived, still less of the probable shortness of your future. A It is not necessary for you to think about the past days and how short it is in your future time. B It is necessary for you to think about the days in your past • because you have little time for the future. C You need not think about your past days. You should consider your future life much. D You should think about the years you have already lived, and the future days you will live.