题目

 China has         in producing clones of cows and goats, and continues to research ways           _______ can benefit mankind.    A. resulted ; that    B. succeeded ; /    C. succeeded ; that   D. resulted ; in which 答案：A在真空中传播的所有电磁波均具有相同的量是（ ）A．波长B．波速C．能量D．频率