按实时电价方法定价，会产生市场盈余，市场盈余的产生主要是由于用户的报价高于发电商的报

生物体死亡后，体内含有的碳-14会逐渐减少（称为衰变）．因此科学家可通过测量生物体遗骸中碳-14的含量，来计算它存活的年代，这种方法称之为放射性碳测年法．碳-14原子核中含6个质子与8个中子，在衰变时，一个中子变成质子，形成新的原子核．下列关于新原子核的说法正确的是（　　）

A．碳原子核，含7个质子，8个中子

B．氮原子核，含7个质子，7个中子

C．碳原子核，含6个质子，7个中子

D．氧原子核，含7个质子，8个中子

两个完全一样的直角三角形能拼成______、______或______．

第三部分:阅读理解(共20小题;每小题2分,满分40分)

阅读下列短文, 从每题所给的四个选项中,选出最佳选项,并在答题卡上将该项涂黑。                        

For thousands of years, people have seen things they didn’t understand in the sky. The United States Air Force first used the words “Unidentified Flying Object” to describe them. Today everyone uses the term UFO. When people see a UFO, it is usually no more than a weather balloon or an airplane. But the Center for UFO Studies goes on to receive hundreds of reports each year.

In 1947 a businessman and pilot, Kenneth Arnold, was flying near Mount Rainier, Washington when he saw nine shiny, round objects flying through the air. He told a newspaper reporter they looked like “pie plates skipping over water.” The reporter used the words “flying saucer（碟子）” in his story and today that is the popular name for UFOs.

The Center for UFO Studies lists three kinds of contacts with flying saucers. “Encounters（遭遇）of the first kind” are reports of unknown objects or lights in the sky. People have “Encounters of the second kind” when a UFO leaves burn marks or other signs on the ground. People report “Close encounters of the third kind” when they see aliens in or near a UFO.

56. Who used the term UFO first?

A. The United States Air force.     B. The Center for UFO Studies.

C. Kenneth Arnold.                     D. A report.

57. The Center for UFO Studies _____.

A. usually sees no more than a weather balloon or an airplane every year

B. is a branch of the United States Air Force

C. receive hundreds of reports every year

D. used “pie plates skipping over water” to describe the UFO seen by the people first

58. Why did the newspaper reporter use the words “flying saucer” to describe the UFO that Kenneth Arnold said he saw?

A. Because the UFO that Kenneth Arnold saw was flat.

B. Because Kenneth Arnold told the newspaper that what he had seen in the sky was round.

C. Because Kenneth Arnold described what he has seen looked like a plate flying in the sky.

D. Because what Kenneth Arnold saw was pie plates flying in the air.

机器人传感器如何分类？方式和种类有哪些？

（）：功成名就：居安思危相当于好逸恶劳：一事无成：（）

A．一雪前耻——沾沾自喜

B．悬梁刺股——闻鸡起舞

C．发愤图强——改过自新

D．成仁取义——唾面自干