单项选择题
A．is certain to succeed B．is successful in his studies C．is considered an educated person D．can grasp any problem
A．the lack of official support B．its high cost C．its failure to help increase production D．the lack of financial support
A．Farmers had few tools before the agricultural revolutions. B．Americans were traditionally self-reliant. C．life on the farm was extremely difficult. D．New tools were designed to the portabl