题目

月球上有丰富的核聚变燃料“He--3”。“He--3”是原子核内含有2个质子和1个中子的氦原子。则氦原子核外的电子数    (    )     A．1    B．2     C．3      D．4 答案：BHe wants to learn more _____ Chinese history. A. for B. with C. of D. about