单选题

　　[阅读理解]The problem of leisure is new. Until very recent times people worked each day to the limit of their strength. Of course there were always a privileged few who had leisure； but most men had to work 12， 14， or even 16 hours a day， six days a week. As late as 1840 the average factory worker labored 72 hours a week. “Sunup to sundown” was the farmer's day， or as another phrase puts it， “from can to can't.”

　　The phrase “from can to can't” means ______.

　　A.from beginning to end

　　B.from birth to death

　　C.from morning to night

　　D.from time to time