Please fill in the blanks according to hints given in brackets.Similarly, if a friend sends you a photo of himself riding on a （独轮平衡车）, you won’t find it too cool. Maybe you’ll just （警告） him, “Hey, （遵守） the traffic rules!” That’s why nowadays “being on wheels” no longer just means “riding a car”. In cities all over the world, new （交通工具）give a unique view: for example, the shared bicycles, both convenient and （节能）. Of course, you may say, “Is that new? Shared electric scooters are common now!” Yes, even（滑板车） that only appeared in playgrounds seem to have become a travel tool for some college students. Sometimes they turn around like a （独行侠） in crowds. And often, they may （摔上一个大跟头）when they are most （得意）their skills.