for dc in range（0,101,5): pwm_obj.ChangeDutyCycle（dc) time.sleep（0.1) 以上这段代码实现了让LED灯由亮变暗的过程。

According to the experiments, many blind people

A．sleep at daytime.

B．can sleep at any time.

C．have different sleep cycle with sighted people.

D．have the same sleep cycle as sighted people.

【35】

A．sleep

B．time

C．work

D．rest

根据以下内容回答题：

When we work and also when we play，we use up energy．The energy may be physical or mental or a(1)of the two．If we set someone at a job and keep him at it continuously(2)rest，ultimately he will break(3)and be unable to go on．If，(4)，he can sloop for a while or do something else for a change，he will be able to work for a longer period of time．Efficiency，then，seems to be to some(5)a matter of the distribution of work and rest periods．In ordinary life work and rest usually take place by(6)．We work during the day，and sleep at night．We continue to(7)between work and rest year in and year out．

We notice first that the work is less efficient at the very beginning than he is after working a short time．This phenomenon，(8)“warming up，”is found in many different activities．Some activities need a long warming up period(9)others need a short period．The speed at which the point of highest efficiency is reached varies(10)individual to individual．

请回答（1）题 查看材料

A.circle

B.combination

C.double

D.sequence

The longest time a human being can survive without sleep is probably ______.

A．five days

B．seven days

C．ten days

D．twelve days

import threading import time lock=threading._RLock() words=["a","b","d","b","p","m","e","f","b"] def increase(): global words for count in range(5): lock.acquire() print("A acquired") for i in range(len(words)): for j in range(i+1,len(words)): if words[j] <words[i]: t="words[i]" words[i]="words[j]" words[j] print("a ",words) time.sleep(1) lock.release() def decrease(): global words for count in range(5): lock.acquire() print("d acquired") i range(len(words)): j range(i+1,len(words)): if> words[i]: t=words[i] words[i]=words[j] words[j]=t print("D ",words) time.sleep(1) lock.release() A=threading.Thread(target=increase) A.setDaemon(False) A.start() D=threading.Thread(target=decrease) D.setDaemon(False) D.start() print("The End") 程序结果： A acquired A ['a', 'b', 'b', 'b', 'd', 'e', 'f', 'm', 'p'] The End D acquired D ['p', 'm', 'f', 'e', 'd', 'b', 'b', 'b', 'a'] D acquired D ['p', 'm', 'f', 'e', 'd', 'b', 'b', 'b', 'a'] A acquired A ['a', 'b', 'b', 'b', 'd', 'e', 'f', 'm', 'p'] A acquired A ['a', 'b', 'b', 'b', 'd', 'e', 'f', 'm', 'p'] D acquired D ['p', 'm', 'f', 'e', 'd', 'b', 'b', 'b', 'a'] D acquired D ['p', 'm', 'f', 'e', 'd', 'b', 'b', 'b', 'a'] D acquired D ['p', 'm', 'f', 'e', 'd', 'b', 'b', 'b', 'a'] A acquired A ['a', 'b', 'b', 'b', 'd', 'e', 'f', 'm', 'p'] A acquired A ['a', 'b', 'b', 'b', 'd', 'e', 'f', 'm', 'p'] 你认为结果可能吗？

听力原文： A Brown University sleep researcher has some advice for people who run high schools: Dont start classes so early in the morning. It may not be that the students who nod off at their desks are lazy. And it may not be that their parents have failed to enforce bedtime. Instead, it may be biologically that these sleepyhead students arent used to the early hour. "Maybe these kids are being asked to rise at the wrong time for their bodies," says Mary Carskadon, a professor looking at problems of adolescent sleep at Browns School of Medicine. Carskadon is trying to understand more about the effects of early school time on adolescents. And at a more basic level, she and her team are trying to learn more about how the biological changes of adolescence affect sleep needs and patterns. Carskadon says her work suggests that adolescents may need more sleep than they did at childhood, not less, as commonly thought. Sleep patterns change during adolescence, as any parent of an adolescent can prove. Most adolescents prefer to stay up later at night and sleep later in the morning. But its not just a matter of choice — their bodies are going through a change of sleep patterns. All of this makes the transfer from middle school to high school — which may start one hour earlier in the morning — all the more difficult, Carskadon says. With their increased need for sleep and their biological clocks set on the "sleep late, rise late" pattern, adolescents are up against difficulties when it comes to trying to be up by 5 or 6 am for a 7:30 am first bell. A short sleep on a desktop may be their bodys way of saying, "I need a timeout." Questions 16 to 18 are based on the passage you have just heard. 16. Why does Carskadon suggest that high schools should not start classes so early in the morning? 17. What might be a reason for the hard transfer from middle school to high school? 18. What is the passage mainly about?17．

A．Adolescents sleep better than they did at childhood.

B．Adolescents have to choose their sleep patterns.

C．Adolescents need more sleep than they used to.

D．Adolescents depend more on their parents.