Weather authorities say parts of western and northeastern China are expected to see moderate snow or sleet this weekend. Slippery, icy roads are always a problem during winter. That's why doctors in Shanghai have come up with these so-called "penguin steps". By imitating the way a penguin walks, it's said that it can prevent falls and a painful bum -- especially for those in the older age bracket. Have you learnt how to "penguin step"?