（Ⅰ）求a，c的值；

（Ⅱ）求sin（B﹣C）的值．

    US City Bans Texting while Walking

    Parents usually teach their children how to cross the street safely, by looking both ways for cars. But do they also teach them to put away their cell phones?

    The city of Honolulu, Hawaii wants everyone to learn that lesson____Beginning on October 24, you could be fined from $15 to $99 if you step into a Honolulu street while looking at your phone. Honolulu is the first major U. S. city to ban what is called "distracted (分散注意) walking. " It recently passed a law in a seven to two vote. The law says; “No pedestrian shall cross a street or highway while viewing a mobile electronic device. "____

    The law's creators hope it will lower the number of people hit and killed by cars in the city. Mayor Kirk Caldwell told Reuters news agency, "We hold the unfortunate distinction (区别) of being a major city with more pedestrians being hit in crosswalks, particularly our elders, than almost any other city in the country. "

    The law includes all electronic devices with screens: cell phones, tables, gaming devices, digital cameras and laptop computers____Pedestrians may use such devices in the street to call emergency services and rescue workers, such as firefighters and police officers.

    ____The Governors Highway Safety Association, or GHSA, says pedestrian deaths in the United States increase 25 percent between 2010 and 2015. That trend continued in 2016 with the number of pedestrian deaths rising to almost 6000, 11% higher than in 2015.

    If you still want to text while walking, you could avoid being fined in Honolulu (and be safer, in general) by using a voice-controlled digital(数字的) assistant such as Siri or Google Assistant____

A. The law does permit an exception.

B. Or you could just wait until you are again, safely, off the street.

C. You will be sentenced to prison while using cell phones in the street.

D. Pedestrian deaths have been increasing as the use of cell phones rises.

E. Texting while crossing the street will soon be banned in the city.

F. The law permits people to watch TV while crossing the street.

G. In other words, do not look at a screen when you cross the street or you could be fined.

—      is it from your home to the railway station?

—It is about twenty minutes by bus.

已知点M（﹣$\frac{1}{2}$，3m）关于原点对称的点在第一象限，那么m的取值范围是____ ．

五四运动后，《共产党宣言》在 中国广泛传播，其中一个重要原因就是与中国传统思想文化有着某些契合点。近年来，关于《共产党宣言》与马克思主义中国化理论的研究也取得了显著成果。阅读下列材料：

材料一：共产主义的特征并不是要废除一般的所有制，而是要废除资产阶级的所有制。但是，现代的资产阶级私有制是建立在阶级对立上面、建立在一些人对另一些人的剥削上面的产品生产和占有的最后而又最完备的表现。从这个意义上说，共产党人可以把自己的理论概括为一句话：消灭私有制……把资本变为公共的、属于社 会全体成员的财产……这时所改变的只是财产的社会性质，它将失掉它的阶级性质。

——《共产党宣言）

材料二：大道之行也，天下为公，选贤与能，讲信修睦。故人不独亲其素，不独子其子。使老有所终，壮有所用，幼有所长，鳏寡孤独废疾者皆有所养……是故谋团而不兴，盗窃乱贼而不作，故外户而不闭，是谓大同。

——孔子

在吾国数千年前，孔子有言日“大道之行也，天下为公”……孔子之理想世界，真能实现，然后不见可欲，则民不争，甲兵亦可以不用矣。今日惟俄罗斯新创设之政府，颇与此相似。

——《孙中山全集》第6卷

材料三：李大钊在1919年7月《每周评论》上发表的《阶级竞争与互助》一文提出：“一切形式的社会主义的根萌，都纯粹是伦理的。协合与友谊，就是人类社会生活的普遍法则……就可以发现出来社会主义者共同一致规定的基础……这基础就是协合、友谊、互助博爱的精神，就是把家族的精神推及于四海，推及于人类全体的生活的精神……”同年，李大钊在《我的马克思主义观》中写到：“我们主张以人道主义改造人的精神，同时以社会主义改造经济组织。不改造经济组织，单求改造人类精神，必致没有效果。不改造人类精神，单求改造经济组织，也怕不能成功。我们主张物心两面的改造，灵肉一致的改造。”

材料四：当代学者罗燕明系统论述了《共产党宣言》与中国的三次结合。他指出第一次结合发生在建党前后，表现为《宣言》的价值观与救亡图存运动的结合。第二次结合发生在建党以后的民主主义革命时期，表现为《宣言》的阶级斗争理论与中国革命实际的结合……实现了马克思主义与中国革命实践相结合的第一次飞跃。第 三次结合发生在社会主义建设时期，表现为生产力观点与社会主义现代化建设实际的结合，这次结合完成了历史主题的转换……实现了马克思主义在中国的第二次飞跃。

——李军林《<共产党宣言>在中国：十年研究述评》