汉字听写大赛经电视热播后，汉字的演变历史再次走进人们的视野。下列汉字字体出现的先后顺序正确的是（    ）

美国大平原主要位于 (      )

党的十八届三中全会以来，许多省市陆续实施“单独二孩”政策．实施“单独二孩”的主要目的是（    ）
①可以迅速提高人口素质            

②可以解决人口增长过快的问题
③有利于缓解劳动力短缺的矛盾        

④有利于缓解人口老龄化带来的问题

选择正确答案

     A dog is walking along a road. It is a big dog. It is carrying a piece of meat. The piece of meat is in the dog's mouth. The dog is walking across a bridge now.There is water under the bridge. The water is very deep. The dog is looking into the water. It can see a dog in the water. This dog has a piece of meat in its mouth, too. The big dog is barking at the dog in the water. It wants its piece of meat, too. The big dog's piece of meat is falling into the water.

在果园里放养蜜蜂对果树的好处是（    ）