之一：——2016年“感动中国”人物，87岁的孙家栋是探月工程总设计师，也是中国第一枚导弹、第一颗人造地球卫星等多个“第一”的技术负责人、总设计师。他领导发射的卫星占中国航天飞行器的三分之一。他少年勤学，青年担纲，是国家的栋梁，“年过古稀未伏枥，犹向苍穹寄深情”。

之二：——2016年“感动中国”人物，朱玥飞，耶鲁大学毕业，现任湖南省衡山县福田铺乡白云村大学生村官，黑土麦田公益（Serve for China）联合发起人。2013年被评为央视“最美村官”，立个人一等功一次。他脚踏实地，俯首躬行，在荆棘和贫穷中拓荒，洒下的汗水是青春，埋下的种子叫理想，守在悉心耕耘的大地静待收获的时节。

之三：——2016年“最美孝心少年”，迟凯琳，女，14岁，辽宁省营口盖州市梁屯学校八年级四班学生。妈妈因车祸去世，爸爸因车祸终身残疾，爷爷瘫在了炕上，姐姐完全失明，奶奶又查出膀胱癌前期，这个家庭怎样维持下去？身体瘦弱的小凯琳，却有一颗火热、善良、坚强的心，年纪虽小，却在人生的花季谱写了一支支动人的道德之歌，她和继母共同撑起六口之家。

你校拟举办“向楷模学习，为人生添彩”主题活动，请你参与并完成如下任务：

如图所示，两绳系一质量为m=0.1kg的小球，上面绳长L=2m，两端都拉直时与轴的夹角分别为30°与45°，问：

如果长期使用耳机可能会损伤对声波敏感的细胞，导致听力下降，而这些细胞位于（　　）

    It's a white Christmas in the United States today, with snow falling from Seattle to Maine.

    Northeast

    Biting winds with snow swept the Northeast.

    Earlier, up to 15 inches of snow fell during a snow storm in Maine, while up to one foot fell in New Hampshire. Winds reached 76 mph on Cape Cod, Massachusetts, while up to 61 mph winds tore through Long Island, New York. Falling snow collected on the runways at Boston's Logan International Airport, causing temporary flight delays.

    The wind was so severe in Pennsylvania and New Jersey that the annual (重演) of George Washington and his soldiers'crossing the Delaware River was canceled, the Washington Crossing Historic Park told ABC News.

    Midwest

    Heavy lake effect snow fell in western Michigan.

    The National Weather Service has issued a wind-chill warning and advisory (公告) from Montana to Michigan. Bitter cold air in the Midwest produced wind chills Monday morning as low as minus 48 degrees in North Dakota and minus 47 in northern Minnesota.

    As this bitter cold made its way east overnight, it was expected to move over relatively mild Great Lakes, producing intense lake-effect snow bands capabie of producing 2 to 4 inches of snow in an hour.

    West Coast

    That storm system moved overnight through the Rockies, bringing more snow and the threat of avalanches(雪崩). The National Weather Service has issued an avalanche warning for the Wasatch Range Mountains outside Salt Lake City.