某同学在上学去的路上，用0.8m/s的速度走完前一半路程，又用1.2m/s的速度走完后一半路程，则他在整个路程中的平均速度是（　　）

改革往往能促进社会的发展和历史的进步，成为人类历史上的“闪光点”。阅读下列材料，回答问题。
材料一  北魏虽然统一了北方，但要巩固政权，还必须解决面临的各种错综复杂的社会矛盾……因为旧贵族的特权和旧部落习俗密切相连，因此当时改革鲜卑旧的习俗，就成为北魏统治阶级急需解决的一个重要问题。
——卢菡著《不可不读的中国历史》

材料二  在甲午战败的强烈刺激下，变法改革也渐渐成为人们的“共识”。朝廷在戊戌变法年间颁布了改革科举、汰冗员、办学堂、修铁路、开银行等学习西方措施的新诏书。
——海天著《沉重的转身》

材料三  克里米亚的失败对俄国的民族主义者和斯拉夫派来说，是一个严重打击。实际上，克里米亚的失败暴露了旧制度的腐朽和落后，旧制度所显示的破产导致旧制度的变革。
——斯塔夫里阿诺斯著《全球通史》

根据拼音写汉字。
①qián        诚   ②shǔ        光   ③急不xiá        择   ④寸积zhū        累

    My dream home is very big and clean. It is near the1. I can watch the sea and2volleyball on the beach.

    My grandparents live 3 us in the big house. 4 room is5the first floor. I always chat with them and help them6some housework on the weekend. On the 7floor, there is a kitchen and a dining room. All the family 8 will have dinner there. My bedroom, study and bathroom are on the third floor. There is a big balcony in my bedroom. I can play games, read books and chat9 my friends there. The furniture（家具） in my house is all made of wood. It is good 10my health. I like 11to music while reading books in my bedroom. I always ask my friends12here. My parents' room is on the fourth floor. It's13very big and clean.

    There is a big and nice garden behind the big house. There are many flowers and14 tall trees in it. In summer, I can sit under the trees with my family. Behind the garden, there is a swimming pool. I can15 freely in it. I think it is very comfortable to live in my dream home.