I find what you say most enlightening.你這一說(shuō),我心里頭亮了.It is interesting and enlightening to consider the derivative of a vector.這對(duì)研究矢量的導(dǎo)數(shù)來(lái)說(shuō)是重要的,而且富有啟發(fā)性.Some of this history is not only interesting but enlightening from a sci...