Before graduating from university in 2023, Lin Xing had experienced this kind of time travel three times. Judging from these limited three experiences, he believed that the length of time he traveled back to the past should be related to the size of the danger.,But the reality is that the whole world is incredibly peaceful. The city he lives in hasn't seen a major crime in decades, and there's no news of any wars happening anywhere else abroad.,Just then, with a light crack, the front door of the classroom swung open.。