Making Light of1 Sleep　　All we have a clock located inside our brains. Similar to your bedside alarm clock， your internal clock2 runs on a 24-hour cycle. This cycle，called a circadian rhythm，helps control when you wake，when you eat and when you sleep.　　This shift4 is natural for teenagers. But staying up very late and sleeping late can get your bodys clock out of sync with the cycle of light and dark5. It can also make it hard to get out of bed in the morning and may bring other problems，too. Teenagers are put in a kind of a gray cloud6 when they dont get enough sleep，says Mary Carskadon，a sleep researcher at Brown University in Providence，RI7 .It affects their mood and their ability to think and learn.　　Scientists have known for a long time that the light of day and the dark of night play important roles in setting our internal clocks. For years，researchers thought that the signals that synchronize the bodys clock8 were handled through the same pathways that we use to see.　　詞匯：　　adolescent n.青少年;adj.青少年的　　sync n. 同步;和諧，協調　　注釋：　　2. your internal clock ：指的是第一句中的a clock located inside our brains ，也即是第二段第一句中的the biological clock 。　　4. This shift：這種調整。指上文所描述的由于生理時間的變化青少年上床時間越來越晚的現象。　　6. gray cloud ：提不起精神的狀態　　創建于1764 年，是世界聞名的美國常春藤聯盟中的一員。　　練習：　　A it controls when we wake，when we eat and when we sleep.　　C it is a cycle also called circadian rhythm.　　2. What is implied in the second paragraph?　　B People after puberty begin to go to bed earlier due to the change of the biological clock.　　D Teenagers go to bed later than they used to due to the light from the computer screen.　　A it is natural for teenagers to stay up late and get up late.　　C during puberty most teenagers experience a kind of gray cloud.　　4. Which of the following statements is NOT true according to the fourth and fifth paragraphs?　　B light gets through our eyes and resets our biological clock.　　D Our internal clock，like the alarm clock，can be reset.　　A The human eye had two light-sensing systems.　　C The human eye could sense the light of day more quickly than the dark of night.　　答案與題解：　　Brains。　　3. B 第三段的最后一句直接給出了答案。　　受的日光來自動調節生理節奏。所以A、B和D都是這兩段中所述內容，C是正確選擇，因為鬧鐘不能自動重新設定時間。　　pathways that we use to see ，也就是說，研究者之前認為人類的眼睛只有一個感光系統。但最新發現卻是，人的眼睛有兩個感光系統。

　　Making Light of1 Sleep　　All we have a clock located inside our brains. Similar to your bedside alarm clock， your internal clock2 runs on a 24-hour cycle. This cycle，called a circadian rhythm，helps control when you wake，when you eat and when you sleep.　　This shift4 is natural for teenagers. But staying up very late and sleeping late can get your bodys clock out of sync with the cycle of light and dark5. It can also make it hard to get out of bed in the morning and may bring other problems，too. Teenagers are put in a kind of a gray cloud6 when they dont get enough sleep，says Mary Carskadon，a sleep researcher at Brown University in Providence，RI7 .It affects their mood and their ability to think and learn.　　Scientists have known for a long time that the light of day and the dark of night play important roles in setting our internal clocks. For years，researchers thought that the signals that synchronize the bodys clock8 were handled through the same pathways that we use to see.　　詞匯：　　adolescent n.青少年;adj.青少年的　　sync n. 同步;和諧，協調　　注釋：　　2. your internal clock ：指的是第一句中的a clock located inside our brains ，也即是第二段第一句中的the biological clock 。　　4. This shift：這種調整。指上文所描述的由于生理時間的變化青少年上床時間越來越晚的現象。　　6. gray cloud ：提不起精神的狀態　　創建于1764 年，是世界聞名的美國常春藤聯盟中的一員。　　練習：　　A it controls when we wake，when we eat and when we sleep.　　C it is a cycle also called circadian rhythm.　　2. What is implied in the second paragraph?　　B People after puberty begin to go to bed earlier due to the change of the biological clock.　　D Teenagers go to bed later than they used to due to the light from the computer screen.　　A it is natural for teenagers to stay up late and get up late.　　C during puberty most teenagers experience a kind of gray cloud.　　4. Which of the following statements is NOT true according to the fourth and fifth paragraphs?　　B light gets through our eyes and resets our biological clock.　　D Our internal clock，like the alarm clock，can be reset.　　A The human eye had two light-sensing systems.　　C The human eye could sense the light of day more quickly than the dark of night.　　答案與題解：　　Brains。　　3. B 第三段的最后一句直接給出了答案。　　受的日光來自動調節生理節奏。所以A、B和D都是這兩段中所述內容，C是正確選擇，因為鬧鐘不能自動重新設定時間。　　pathways that we use to see ，也就是說，研究者之前認為人類的眼睛只有一個感光系統。但最新發現卻是，人的眼睛有兩個感光系統。