average velocity和average speed区别在哪?

average velocity和average speed区别在哪? average speed 和average velocity 有什么区别? velocity 和speed的区别 "speed"和'velocity"的区别 average和general的区别 on an average和on the average在用法上的区别 average an average of 和the average of的区别 the average of和 a average of 有区别吗 in an average 和 on average的区别 speed和velocity有什么区别? ae中speed和velocity区别