拓扑学是对图形在任何变形下保持不变的性质的研究。
The best stories are those that leave something to the imagination.
Among thousands of people, you meet those you've met. Through thousands of years, across the boundless wilderness of time, you happen to meet them, neither earlier nor a bit too late. There is nothing to be said except to ask lightly, "Oh, you're here too?"