辽宁舰跑道长200m．飞机在航母上滑行的最大加速度为6m/s²，起飞需要的最低速度为50m/s．那么，飞机在滑行前，需要借助弹射系统获得的最小初速度为（   ）

材料一：这几年，每到秋冬，我国中东部地区不时会遇到雾霾天气。“世界上最远的距离，是牵着你的手，却看不见你的脸”……各类关于雾霾的段子近期广为流传。
材料二：今年地方两会上，雾霾治理成为提及频度最高的热点之一，各地纷纷出重拳治霾。***表示，我们说要向雾霾等污染宣战，可不是说向老天爷宣战，而是要向我们自身粗放的生产和生活方式来宣战。 

已知函数 f（x）=e^x（e^x﹣a）﹣a²x．（12分）

B

Beyond Beyond (2014 )

    The film (Beyond Beyond) is the story about a little rabbit, Johan, who sets out on an amazing journey to find his mother and reunite(使重聚) her with her family. The film was first produced in Sweden.

    It's such a wonderful movie that I've seen it twice. The beautiful scenes impressed me a lot.

— Lucy

    My eight-year-old son and I went to see this movie this Tuesday. We were really surprised at how exciting it was. I would recommend（推荐）this cartoon to the whole family.

 — Mrs. White

艺复兴时期，意大利人热衷于讨论