C
RIDING in school buses in the early morning，then sitting in poorly lit classrooms，are the main reasons students have trouble getting to sleep at night，according to new research．
Teenagers，like everyone else，need bright light in the morning to allow their circadian rhythms(生理节奏)to get into step with nature's cycles of day and night．
If they don't get blue 1ight in the morning，they get to sleep an average of six minutes later at night，until their bodies are completely out of sync(同步) with the school day，researchers from Rensselaer Polytechnic Institute in New York said last month．
The finding was made by fitting goggles(护目镜)that block blue light from the sun to a group of students．The researchers discovered that their circadian rhythms were greatly affected．
Parents and teachers have been complaining in recent years that teens stay up too late at night，then fall asleep in class the next morning and do poorly in school．The new findings provide a possible explanation for the problem．
At the root of the research is the circadian rhythm, the body's natural sleep and waking cycle．Even though the Earth makes a full rotation(旋转)in 24 hours，the body's circadian cycle is about 24 hours and six minutes 1ong．The cycle is mediated(调节)by a chemical called melatonin(褪黑激素)．The body starts to produce it about two hours before it is time to sleep and, in the absence of blue 1ight，the body produces about six minutes later each day.
In the study, the researchers studied 11 students at Smith Middle School in New York, which was designed so that a lot of sunlight  reaches classrooms．
On a Friday night，the researchers measured what time the 11 students’ bodies began releasing melatonin．On Monday morning，the students were sent to school with orange goggles that blocked most blue light from their eyes to mimic(模拟) the conditions found in many---if not most--schools．
By the end of the week，the students were releasing melatonin 30 minutes 1ater in the evening---an average of six minutes a day--and going to sleep correspondingly(相应的) later．
“This is our first field study，”said lead author Mariana G．Figueiro．He said they would like to repeat it in larger studies and for longer periods of time。
If the findings are repeated，a variety of solutions are available．Ideally, new schools would be built to allow more natural sunlight into the classrooms．Students could also be exposed to more sunlight outside．
68. According to the findings related in this article, many teenagers stay up late because_______
A. they lack melatonin in their bodies
B. they have to get up so early to catch the school bus
C. their circadian rhythms are in disorder
D. they do not get enough blue light in the morning
69. According to the findings, a student who normally slept at 10:00 pm, but who spent 10 days in a poorly lit classroom, would probably be falling asleep at___________after the period.
A. 12:00pm   B. 11:30pm   C. 11:00pm   D. 10:00pm
70. What does the article tell us?
A. Unlike adults, teenagers tend to feel sleepy during daytime.
B. The sunlight is the only thing that can affect our circadian rhythms.
C. If the findings prove correct, solutions could be found to teen sleeping problems.
D. Most schools have small windows and the classrooms are poorly lit.
71. The main point of the article is to___________
A. warn teenagers not to stay up late or sleep in class
B. report on some new findings related to teenagers' sleeping problems
C. give suggestions on how to build schools
D. advertise goggles which can protect the eyes from the sun

The group of research workers are said to ________ to the dangerous nuclear radiation while they carried out their rescue task.

A. be exposed          B. have been exposed       C. exposed       D. be exposing

阅读下面短文，根据以下要求：1）汉语提示；2）首字母提示；3）语境提示，在每个空格内填入一个适当的英语单词，所填单词要求意义准确、拼写正确。

注意：原行没有错的不要改。

Volunteering not only has a meaningful and positive effect on your

1.neighborhood but also can have many          (益处) to you. First, whether

2.you help c      the rooms for the old, do something for the disabled,

3.        teach the children to sing, you’ll gain some valuable skills and

4.experience. Then by        (使用) them you can make your study or

5.your future job better. Volunteering b      together a variety of people

6.from different backgrounds. You’ll be exposed         a new environment.

7.And maybe you’ll learn w      you can’t learn at school. It can also help

8.you reward the society, break down barriers of         (误解), and even

9.have fun. B       , it is a good way for us students to learn and

10.communicate with others, and it is        great importance to our society.

Seasonal influenza is characterized by a sudden fever, cough, headache, muscle and joint pain, sore throat and runny nose. Most people recover from fever and   1  symptoms within a week without requiring medical attention. But influenza can  2  severe illness or death in people at high risk. The time from infection to illness is about two days.

Yearly influenza epidemics can  3   affect all age groups, but the highest risk of complications occur among children younger than age two, adults age 65 or older, and people of  4   age with certain medical conditions, such as chronic heart, lung, kidney, liver, blood or metabolic diseases, or weakened immune systems.

Seasonal influenza  5   easily and can sweep through schools, nursing homes or businesses and towns. When an   6    person coughs, infected droplets get into the air and another person can breathe them  7    and be exposed. The virus can also be spread by hands infected with the virus.  8    transmission, people should cover their mouth and nose with a tissue when coughing, and  9   their hands regularly.

Drugs for influenza are   10   in some countries and effectively prevent and treat the illness. Some influenza viruses develop  11    to the antiviral medicines, limiting the effectiveness of treatment.

Influenza epidemics occur    12   during autumn and winter in temperate regions. Illnesses result in hospitalizations and deaths mainly among high-risk groups. Worldwide, these annual epidemics result in about three to five million   13     of severe illness, and about 250 000 to 500 000 deaths.

Influenza can cause serious public health and economic problems. In   14    countries, epidemics can result in high levels of worker absenteeism and productivity   15   .   16    most people recover from a bout(轮) of influenza, there are large numbers of people who need hospital treatment and many   17    die from the disease every year.   18     is known about the effects of influenza epidemics in developing countries.

The most    19   way to prevent the disease or severe outcomes from the illness is vaccination. Vaccination is especially important for people at higher risk of serious influenza complications, and for people who live with or care  20    high risk individuals.

(  ) 1. A. its                 B. it’s                    C. all                    D. other

(  ) 2. A. cause                 B. lead                  C. result                D. bring

(  ) 3. A. lightly           B. slightly             C. seriously           D. heavily

(  ) 4. A. all                 B. any                   C. no                    D. both

(  ) 5. A. goes              B. spreads              C. comes        D. happens

(  ) 6. A. to infect        B. infecting           C.  infected          D. infect

(  ) 7. A. off                B. away                 C. out                   D. in

(  ) 8. A. To prevent     B. To protect          C. To prepare         D. To prefect

(  ) 9. A. wash             B. washing            C. to wash             D. washed

(  ) 10. A. free             B. available           C. useful               D. helpful

(  ) 11. A. assistance     B. resistance          C. consistence        D. preference

(  ) 12. A. monthly              B. weekly              C. daily                 D. yearly

(  ) 13. A. pieces          B. states                C. conditions         D. cases

(  ) 14. A. developed    B. developing        C. big                   D. small

(  ) 15. A. lose             B. losses                C. loose                 D. lost

(  ) 16. A. For             B. Because             C. While               D. Whether

(  ) 17. A. /                 B. which               C. do                    D. who

(  ) 18. A. Little           B. Much                C. Few                  D. Lot

(  ) 19. A. affective      B. effective            C. attractive           D. aggressive

(  ) 20. A. about           B. of                     C. for                    D. to

I want my son __________ all sorts of people with different values and beliefs.

A. being exposed to  B. exposing to

C. to be exposed to  D. expose to