冷沉淀的保存最佳温度为（）。 A.2～6℃ B.－20℃以下 C.－80℃以下 D.

有一种新型“即热饭盒”，其加热原理是水和镁、铁的混合物发生反应。使用时发生的反应有：Mg＋2H₂O=X＋Mg(OH)₂。请回答：

（1）其中X的化学式是__________。参考“部分酸、碱、盐溶解性表” Mg(OH)₂的溶解性为___________。

（2）上述化学反应的基本反应类型属于____________。

TANG Dynasty writer Du Mu once wrote in a poem titled Qingming: "The ceaseless drizzle drips all the dismal day; So broken-hearted fares the traveler on the way.Where can a wine house be found to drown his sadness ?A cowherd points to Almond Flower (Xing Hua) Village in the distance."

Qingming, the traditional tomb-sweeping day on the Chinese lunar calendar, falls on April 4 this year. Qingming Jie was proclaimed a Chinese national holiday in 2008. It is a time for remembering loved ones who have departed (去世). People visit their ancestors’ graves to sweep away the dirt and get rid of any weeds. They also leave offerings (祭品) of food and flowers, and burn incense (香) and paper money. Chinese tombs are usually built in the woods or on mountains, far from the city. It is believed that an area that faces south, with many pine trees, is a proper place for a tomb. People believe such a place will make the ancestors happy, and in return, they will look after the living family.

Nowadays, more and more residents are choosing environmental-friendly ways to spend the holiday such as flower sacrifices and memorial ceremonies on the Internet or at home. As one of the traditional ways to celebrate Tomb-sweeping Day – burning paper or incense – isn't exactly good for air quality.

In contrast to the sadness of the tomb sweepers, people also enjoy hope of Spring on this day. The Qingming Festival is a time when the sun shines brightly, the trees and grass become green and nature is again lively. Since ancient times, people have followed the custom of Spring outings. At this time tourists are everywhere.

Many people fly kites on Tomb Sweeping Day. They are usually made from a bamboo crossbow with coloured paper. The kite vibrates and buzzes as it rises into the sky, counterbalanced by its tail. Large kites can be as broad as three metres across, with a tail of six to ten metres. Most kites have a rectangular shape, and many have patterns of crabs, centipedes, butterflies, dragonflies, or Chinese characters such as "good fortune" or "long life". (361words)

小题1:What’s the main idea of the second paragraph?

A．The cultural difference between the east and the west.

B．The traditional customs on tomb-sweeping day.

C．Various ways to care for the dead in the world.

D．Qingming Festival小题2:All of the following practices are mentioned on tomb-sweeping day EXCEPT_____ .

A．Weeping over the passed-away.

B．Flying kites made from bamboo and paper

C．Sending flowers to their ancestors’ graves.

D．Burning incense and paper money for the dead.小题3:Which of the following is correct according to passage?

A．Du Mu ,the well-known poet in Song Dynasty wrote a poem about Qing Ming.

B．Qingming Festival used to be a Chinese national holiday.

C．People have the custom of flying kites on Qing Ming.

D．Those whose ancestors were buried in proper places will have a bright future.小题4:The writer write the passage in order to____________ .

A．enable us to observe traditional tomb-sweeping day.

B．show traditional and present ways to spend Qingming Festival .

C．educate people to show their respect to the ancestors

D．raise people’s awareness of environmental protection.

巴塞尔委员会对市场风险内部模型提出的要求，表述不正确的是( )。

A．置信水平采用99%的单尾置信区间

B．持有期为10个营业日

C．市场风险要素价格的历史观测期至少为半年

D．至少每3个月更新一次数据

急性梗阻性化脓性胆管炎的主要病因是

A．壶腹部肿瘤

B．胆管狭窄

C．胆道蛔虫

D．胆道炎症

E．胆道结石

2013年是毛 * * 《在延安文艺座谈会上的讲话》发表71周年。71年来，“文化为什么人服务”的思想激励一代又一代文艺工作者走出书斋，投身沸腾的生活，走入人民大众之中，创作出一批批无愧于时代和人民的作品。这说明（）

①优秀文化可以丰富人的精神世界，增强人的精神力量

②文化对人的影响是深远持久的

③文化有其自身的传承性和相对独立性

④文化是人们认识世界和改造世界的物质力量

A．①②

B．①④

C．③④

D．②③