西亚村庄的房屋墙厚、窗小的原因是（    ）。

—Yesterday , my father bought me a new mobile phone as a present , but I don't know how to use it. 

—Why not read the ________ first before using it ?

G20杭州峰会会标是别具匠心的桥的图案。桥是杭州特有的杭州文化符号，桥作为连接双边，构建对话的载体，代表了文化和经济的开放、包容、理解和沟通，很好地诠释了G20峰会的精神、会标图案的寓意包括（    ）

①互信互疑  战略结盟      ②沟通交流  携手前行

③深化合作  互利共赢      ④凝聚共识  互学互鉴

    Yesterday，Amy and Mary went to the zoo by bike. They saw pandas, lions, monkeys and elephants. They were very happy. They were thirsty, so they bought a watermelon. Amy carried the watermelon on her bike. But it fell off her bike and bumped her foot(脚).

如图，在方格纸中选择标有序号①②③④的一个小正方形涂黑，使它与图中阴影部分组成的新图形为中心对称图形，该小正方形的序号是（　　）