BEIJING, March 31 (Xinhua) -- At the National Innovation Center for Digital Fishery in Beijing, two robotic fish with a sleek, metallic finish swim gracefully in a breeding tank, showcasing ...

潮汐是由月球和太阳的引力，以及地球自转产生的惯性力共同作用下，引起的海水周期性涨落现象。简单来说，就是海水每天都会有规律地升高和降低。涨潮时，海水水位上升，淹没部分陆地；退潮时，海水水位下降，露出海滩。这种周而复始的运动，就是潮汐。©Linda ...

Modern life makes us tired, right? But research from societies in Africa and South America suggests people in the ancient ...