Thời gian đi du lịch
You may have heard physicists describe the moon as being 1.3 light-seconds away, or the sun as 8 light-minutes away, and thought "what is this nonsense? measuring distances with...
1
annotations
North Korea is sometimes called the land of whispers; people don't say things out in the open. They generally whisper to each other and then quickly walk away! It's one of the most...
