第5题: [单项选择]It was only after some progress ______ in the use and development of electric current that men began to realize the importance and possibilities of magnetism. 参考答案:D 答案解析:[解析] 分析题干可知,本题陈述的呈发生在过去的事实,而非虚拟,故排除[B]和[C]。由only after... that...“只有…之后,才…”可知,电流的使用和发展上的进展发生在人们意识到磁场