在下列语句中：

①无理数的相反数是无理数；

②一个数的绝对值一定是非负数；

③有理数比无理数小；

④无限小数不一定是无理数．

其中正确的是（　　）

补写出下列句子中的空缺部分。

①《使至塞上》中，作者以“蓬”“雁”自比，表达内心的激愤和抑郁之情的句子是“____，归雁入胡天。”

②《离骚》中表明作者保持清白为正道而死，也是以古贤为榜样的两句：“____，____。”

③在《赤壁赋》的开头，苏轼写自己与朋友泛舟赤壁之上，朗诵《诗经·陈风》中的《月出》篇，即文中所谓“____，____。”

④子贡问以仁。子曰：“____，____。居是邦也，事其大夫之贤者，友其士之仁者。”（《卫灵公》十）

       In Zhangdian High School, Wuhan City, teachers and students often see a man collecting trash.

       The man is Luo Yiming, a 54-year-old history teacher in the school. His wife is a dormitory supervisor. Their two sons have already grown up and are working.

       To ask students to save some things, take care of the environment and do good

 things, Mr. Luo has been collecting trash since 1997 in his free time. In order to store more trash, he even put the trash into his small room.

       He sells the trash and gets some money. But he doesn't keep the money himself but helps Students. In the past 16 years, with the money of over RMB 22,000,he helped more than 60 poor students. At the same time, he helped 5 poor villagers, too. After Wenchuan earthquake, Mr. Luo gave away RMB 2,000 to the quake area.

       "Mr. Luo's kindness influenced us greatly. We should all learn from him. " said Pan Hongmei , one of the students Mr. Luo helped.

       "Saving is a kind of generosity and giving is a kind of happiness. " said Mr. Zhong, the headmaster of the school , "Mr. Luo gives us a best example. "

汉武帝从匈奴手中夺去了（   ）