题目

The firm was successfully run and ________， he owed his success to the support of his friends. A. looking back B. looked back      C. to look back         D. when looked back 答案：A 将金属与金属(或金属与非金属)加热熔合在一起就能形成合金．根据下列金属的熔点、沸点推测，其中不可能形成合金的是 A． Fe、Cu B． Al、Na C． Fe、Na D． Cu、Na