Future Certificate Restriction
冯道出来做事，历仕多朝，却因宋儒为了确立忠君思想而被树为负面典型，背负上骂名。事实上，在五代、宋初人的记忆中，冯道的行为不仅并不构成伦理问题，甚至是道德楷模。。whatsapp对此有专业解读
。关于这个话题，手游提供了深入分析
In addition to being less dependent on imports, the U.S. economy is much less oil-intensive than it used to be, producing more economic value with far less oil use today than in the past.
std::asin() time: 12650 ms，更多细节参见wps
der(R1 & R2) = combine der(R1) and der(R2) with intersection