单项选择题
A．he didn’t live very long with them B．the family was extremely large C．he was too young when he lived with them D．he was fully occupied with observing natur
A．As B．Like C．Since D．Because
A．products should be made with less cost but higher efficiency B．products should be sold at low prices in large quantity C．products should be sold at high prices in large quantity D．standards must be established in his plants