If you will buy stock in an electrical utility which has a guaranteed revenue stream, because no matter how bad the economy gets, a lot of people still use electricity, you don't expect it to fluctuate a lot.

如果你在有着,保障性年收入的电气供应股票投资，因为不管经济变得怎么查，人们还得用电，它不会降多少。

麻省理工公开课 - 计算机科学及编程导论课程节选