人类留下的痕迹往往是伤痕。
电子不是一个物体，而是电磁场的一种表现。
解析：强调实践的重要性。
I do not know much about it, but I think some of America's best young men served in this war.
The number one benefit of information technology is that it empowers people to do what they want to do. It lets people be creative. It lets people be productive. It lets people learn things they didn't think they could learn before, and so in a sense it is all about potential.
