Why not fly to Beijing?
What do you want to do in the summer holiday?Why not fly to Beijing?有这么说的吗？嗯，有的 why not do sth 为什么不做某事呢fly to beijing 搭乘飞机飞往北京（不是自己长翅膀飞O(∩_∩)O）应该是How about going to Beijing by plane in summer holiday? 吧！就是改的地方不一样why not do sth =how about doingby plane= fly to看你选择，个人认为都没错的。你可以斟酌采纳