(2015·廣西柳州3月模擬)It is 7 am and the alarm is going off.You know you have to be out of bed to catch the bus.But the urge to bury yourself in the bed is ever so strong.Sounds familiar? Why is it that teens find it difficult to get themselves out of bed in time every morning or stay sharp and focused during the first couple of hours of school?

During adolescence，the body goes through many changes and these include a shift in sleep patterns.Researchers from MIT have been tracking the body’s need for sleep in teenagers.They found that though adolescents need as much as 9.5 hours of sleep a day，they get to bed later and later with each passing year.In fact，the sleep cycle shifts later by as much as 12 to 18 minutes each year between the ages of 10 and 20 ! So by the time a 10­year­old who sleeps at 8 pm grows to be 17 or 18，his body naturally wants to stay up till 10：30 pm or 11 pm.

According to researchers，this is because of a hormone called melatonin (褪黑激素) that is secreted (分泌) by the pineal gland—a tiny structure deep inside the brain.Melatonin regulates the body’s natural day­night rhythms.It causes a person to become sleepy by lowering his body’s core temperature.In teens，melatonin is secreted much later in the evening and continues to increase throughout the night.This makes it difficult for teens to fall asleep earlier as they did in their younger years.Likewise，the effect of melatonin continues until much later in the morning，making it hard for them to wake up early.

A study found that at least one in four teens is tired and falls asleep in school at least once a week.During sleep，important body functions and brain activities happen.So how can teenagers get their sleep enough? The American Academy of Pediatrics (AAP) recommends that middle and high schools should start later—not before 8：30 am.This should give teens some more time to sleep at night.

【解題導語】　本文是一篇說明文。早睡才能早起，晚睡會導致早上賴床，睡覺周期的改變實際上受制于大腦中一種被稱為褪黑激素的荷爾蒙。

5.From Paragraph 2，we can learn that if you sleep late，the next day you should ________.

A.stay sharp B.skip breakfast

C.get up late D.stay up late

解析：選C。細節(jié)理解題。文章第一段提到為什么孩子們早上不愿起床，第二段緊接著分析原因，說明孩子們睡覺晚是他們早上賴床的原因，即C項正確。

6.What does the underlined word “this” in Paragraph 3 refer to?

A.The students want to stay up.

B.The shifts of the sleep cycle.

C.The pineal gland secretes melatonin.

D.The adolescents sleep late.

解析：選B。代詞指代題。第二段提到了睡覺周期的改變，第三段緊接著解釋造成這一現(xiàn)象的原因，因此this指睡覺周期的改變，即B項正確。

7.The teens go to sleep later than before because ________.

A.melatonin is secreted much later

B.melatonin regulates the sleep time

C.they sleep a lot in the daytime

D.they need to finish their homework

解析：選A。細節(jié)理解題。根據(jù)文章第三段中的“In teens，melatonin is secreted much later in the evening and continues to increase throughout the night.”可知，孩子們睡覺晚是由褪黑激素分泌晚造成的，即A項正確。

8.According to AAP’s recommendation，middle and high schools should ________.

A.let teens sleep in the day

B.let the students be active

C.delay the start time

D.start later at 8 am

解析：選C。細節(jié)理解題。根據(jù)文章最后一段的倒數(shù)第二句話可知，AAP建議初中和高中上午上課的時間應該推遲，即C項正確。

C

(2015·大連高三雙基測試)Any list of the greatest thinkers in history contains the name of the brilliant physicist Albert Einstein.His theories of relativity led to entirely new ways of thinking about time，space，matter，energy，and gravity.Einstein’s work led to such scientific advances as the control of atomic energy，even television as a practical application of Einstein’s work.In 1902 Einstein became an examiner in the Swiss patent office at Bern.In 1905，at 26，he published four of his five major research papers.The first one provided a theory explaining Brownian movement，the zig­zag motion of microscopic particles in suspension(懸浮液).The second paper laid the foundation for the photon(光子)，theory of light.In it he proposed that light is composed of separate packets of energy，called photons.A third paper contained the “special theory of relativity” which showed that time and motion are relative to the observer，if the speed of light is constant and the natural laws are the same everywhere in the universe.The fourth paper was a mathematical addition to the special theory of relativity.Here Einstein presented his famous formula，E=mc2，known as the energy mass equivalence(等價).In 1916，Einstein published his general theory of relativity in which he proposed that gravity is not a force，but a curve(曲線) in the space­time continuum(連續(xù)體)，created by the presence of mass.

Einstein spoke out frequently against nationalism，the rising of one nation above all others.He opposed war and violence and supported Zionism，the movement to establish a Jewish homeland in Palestine.When the Nazis came to power in 1933，they criticized his ideas.He then moved to the United States.In 1939 Einstein learned that two German chemists had split the uranium atom.Einstein wrote to President Franklin D.Roosevelt warning him that this scientific knowledge could lead to Germany developing an atomic bomb.He suggested the United States begin its own atomic bomb research.

【解題導語】　本文是一篇記敘文，主要介紹了思想家、物理學家愛因斯坦對人類的偉大貢獻及其人生閱歷。

9.Einstein left for the United States ________.

A.because of political reasons

B.because he loved the United States

C.because of his sickness of Germany

D.because he was employed by the United States

解析：選A。推理判斷題。根據(jù)第二段第三、四句“When the Nazis came to power in 1933，they criticized his ideas.He then moved to the United States.”可知，1933年納粹黨執(zhí)政后，批判了他的理論，于是愛因斯坦便去了美國;由此可推知，愛因斯坦是迫于政治原因去美國的。故答案選A。

10.Television is mentioned in the text as ________.

A.Einstein’s discovery

B.a great invention of Einstein

C.the purpose of Einstein’s work

D.a successful use of Einstein’s work

解析：選D。細節(jié)理解題。根據(jù)第一段第三句“Einstein’s work led to such scientific advances...even television as a practical application of Einstein’s work.”可知，愛因斯坦的工作成果推動了科學的發(fā)展，電視是對他的理論的實際應用。故答案選D。

11.According to the text，Einstein disagreed on ________.

A.nationalism

B.the defeat of the Nazis

C.atomic bomb research in the United States

D.the establishment of a Jewish homeland in Palestine

解析：選A。細節(jié)理解題。根據(jù)第二段第一句“Einstein spoke out frequently against nationalism，the rising of one nation above all others.”可知，愛因斯坦反對民族霸權(quán)主義。故答案選A。

12.According to the text，Einstein is known as the following EXCEPT a ________.

A.physicist B.politician

C.peace lover D.thinker

解析：選B。細節(jié)理解題。根據(jù)第一段第一句“Any list of the greatest thinkers in history contains the name of the brilliant physicist Albert Einstein.”可知，愛因斯坦是位偉大的思想家和物理學家;根據(jù)第二段中的“Einstein spoke out frequently against nationalism...opposed war and violence”可知，愛因斯坦反對民族霸權(quán)主義，反對戰(zhàn)爭與暴力，由此可知，他是個愛好和平的人。文中沒有提到他是一位政治家。故答案選B。