单项选择题
A．it was man' s first real invention B．all transportation depends on it C．every machine depends on it D．both B and C
A．a group of early hunters B．the first men on earth C．a great prehistoric thinker D．the man who made the first cart
A．Jobs as doctors and lawyers. B．Jobs in service industries. C．Jobs in areas without sex discrimination. D．Jobs in areas where women are respecte