Who invented the world's first four-wheeled car?
A、Carl Benz
B、Gottlieb Daimler
C、Rudolf Diesel
D、Henry Ford

单项选择题边际产量低于平均产量时（）

多项选择题Fiction can inspire us, intrigue us, scare us and engage us in new ideas. Some examples of works of fiction are , fairy tales, short stories, and any novels. A、legends B、folk tales C、reports D、 histories