Is it possible that this substance,spontaneously and without any previous excitation,emits some invisible,highly penetrating radiation that can pass without difficulty through the cover of the box and the black paper and affect the photographic emulsion?是什么意思_Is it possible that this substance,spontaneously and without any previous excitation,emits some invisible,highly penetrating radiation that can pass without difficulty through the cover of the box and the black paper and affect the photographic emulsion?在线翻译_英语_读音_用法_例句