13．杭州市长在开放式决策研讨会上表示，“老百姓有权知道政府在做什么！”市政府的重要活动或全体会议今后都将进行视频直播，杭州各区县市也将因地制宜，通过网络直播形成互动。杭州市政府“开放式决策”有利于     
①充分保障公民的知情权，监督权 ②从根本上保证民主决策的落实 ③国家机关改进作风，更好的履行职能 ④依法行使表达权是公民参与国家管理的基础和标志

张强同学想探究20世纪50—70年代美苏争霸的历史，他上网查找的资料中，不应该有

   There are four seasons in a year. They are spring, summer, autumn and winter. For all my friends, every season is good.

   Wang Dong likes flying kites and climbing hills. She says when spring comes, the days are getting warmer and longer. And everything begins to grow. The wind is not very strong. It’s the best time to fly kites. And when you climb the hills, you can enjoy yourself. So she often says spring is her favourite season.

   “Swimming is my favourite sport,”says Anne. “When summer comes, I often go swimming in the rivers or lakes with my friends. ”You can enjoy yourself in the water. And you can swim like a fish there.

   “I often go climbing hills with my father during the long vacation of the National Day, ”says Liu An. “My father often tells me that I can see lots of beautiful things if I stand on the top of a hill. ”So he likes autumn best of all.

   Bob says he likes winter very much. He says, “I’m very happy when I am playing with snow.”He is making a snowman now.

下面语句有两处语病，请将改正后的句子写在横线上。

多部门联合开展了一系列“满足阅读需要，繁荣文学创作”的活动，并且制定了工作万法。

                                                                                                                         

已知α为钝角，β为锐角，且sinα=$\frac{4}{5}$，sinβ=$\frac{12}{13}$，则$\cos \frac{\alpha -\beta }{2}$的值为（　　）