A．People in Western countries have very mixed feelings about the sun. On the one hand it evokes memories of beaches, summer holidays and playful times. Children's books often personify the sun as a smiling, happy face—typically contrasted with angry, moody rain clouds. In fact, the sun has such positive connotations that the descriptor 'sunny' refers not only to a state of weather but also to 'cheery, cheerful, or joyous' moods and dispositions amongst humans. On the other hand, many people fear the sun because of its association with cosmetic degeneration that can cause people to look much older than they actually are. Even more seriously, many people see the sun as a killer— this is because excessive sun exposure can lead to skin cancer which has a very high mortality rate. So is the sun our friend or a foe? The answers are complex and contradictory.
B．Let's start with the worst news about the sun. It is a carcinogen. As the National Toxicology Program Report on Carcinogens from the Department of Health and Human Services reports, broad-spectrum UV radiation and solar radiation (what is known as 'sun rays' ) are thought to contribute to most of the estimated 1.5 million skin cancers diagnosed in the United States each year. This gives the sun the unfavorable distinction of being the leading carcinogen in the United States—ahead of genetic mutations, bad diets, cigarettes, alcohol, chemical exposure and other lifestyle factors. Of these diagnoses, 8,000 sufferers will perish from the condition. The primary cause of this mortality is monastic melanoma—moles that become cancerous and then spread mutated cells into the lymph nodes and eventually through the rest of the body.
C．Even if you are lucky enough to avoid skin cancer, the sun can still have damaging effects on your skin. This is known as premature aging, so-called because sun damage mimics the skin's natural aging process, but does so at a much earlier age. The sun causes premature aging by breaking down and mutating collagen—a fibrous, 'glue'-like substance that supports and connects tissue and is responsible for the firmness, suppleness, elasticity and overall appearance of the skin. Skin's collagen production slows and eventually stops due to aging anyway, but sun exposure accelerates this process. It also mutates collagen cells, producing visible abnormalities on the skin. The slowing collagen production appears as wrinkles, sagging and fine lines, while the mutated cells can take the form of a leathery skin texture, facial ruddiness and blemishes known as liver spots. Together these can dissolve signs of youth and vitality from a person's looks—an image that contrasts starkly with the smooth, tanned and youthful-looking models we often associate with summer!
D．The sun does have a lot of positive things to offer humans, however. Firstly, it staves off Seasonal Affective Disorder (SAD), an appropriate acronym for a mood disorder caused by insufficient exposure to light—as such, it is typically associated with winters and is sometimes called 'winter blues' or 'winter depression'. SAD, once treated with skepticism by health experts but now widely acknowledged to be a legitimate condition, can create a number of distressing problems. Sufferers may oversleep and find it difficult to be roused in the morning, crave 'comfort foods' high in carbohydrates, lack energy, find it difficult to concentrate and may withdraw from social exposure. Together these symptoms can lead to depression, pessimistic feelings of hopelessness and an inability to find pleasurable activities. Researchers are not yet sure of the exact physical mechanism that causes SAD, but they do know that exposure to bright life is an effective remedy. The sun definitely has a palliative effect here.
E．In other ways, the health-improving effects of the sun can be even more powerful. These effects typically relate to Vitamin D, of which the sun is a great source for two reasons. Firstly, it is completely free, and secondly, our bodies have natural mechanisms that prevent an overdose from internally generated Vitamin D from the sun. Although this vitamin can be sourced from milk, cod liver oil and supplements, solar radiation is still the primary source for most humans. It's preventative role is important: Vitamin D seems to protect against prostate, breast, colon, kidney and ovarian cancers, benefit bone health, as well as reduce overall mortality and the occurrence of cardiovascular events— mortality from strokes and heart attacks is up to forty percent higher in some countries during winter months, a connection linked to lack of sun exposure. In fact, skin cancer rates rise with proximity to the equator amongst light-skinned people, but the prognosis of most other cancers is exactly the opposite. Indeed, the overall benefits of sun exposure outweigh the risks when it comes to cancer, even though the sun is a well-documented carcinogen.
F．Ultimately, moderation and protection may be the key when it comes to sun exposure. This is true of other carcinogens such as alcohol as well—studies suggest that binge drinkers and teetotalers experience higher levels of many health problems than people who drink moderate amounts of alcohol on social occasions. Healthy access to the sun involves wearing broad-spectrum sunscreen before every exposure (even in winter)and not staying in the sun any longer than is necessary, which is about five minutes for adequate Vitamin D exposure. With these simple steps, the sun once again becomes our friend and not our foe.
Reading Passage 1 has six paragraphs, A-F.
Which paragraph contains the following information?
Write the correct letter, A-F, in boxes ] -6 on your answer sheet.
A description of the physical process that makes someone look older?
Recommendations for how to be safe in the sun?
Examples of emotional ailments that contact with the sun can treat?
Evidence that the sun can lower death rates?
An explanation of how a single word can have contrasting connotations?
Several causes of cancer?
Choose the correct letter, A, B, C or D. Write your answer in box 7 on your answer sheet. Which of the following is NOT given as a symptom of premature aging?
Do the following statements agree with the information given in Reading Passage 1 ?
Experts no longer consider SAD to be a health problem?
Artificial sources of light are not very good at treating SAD?
The sun cannot give us too much Vitamin D ?
Most people get their Vitamin D from the sun?
The sun can both cause and prevent cancer?
[Humans have long been fascinated by the possibility of extra-terrestrial life. Novels, films and folk-tales have encouraged curiosity and speculation about what might be 'out there' in space. More recently, scientists have joined in on the collective wonderment after the first discovery by astronomers of a new planet—Giles 581g—that could almost certainly support such organisms. In fact, Steven Vogt—one of the two astronomers credited with discovering the planet—has declared that 'the chances of fife on this planet are 100 percent' and that he has ' almost no doubt about it'.]
A．Although we currently know very little about Giles 581g, a couple of its features strongly indicate that this planet might harbor the existence of organisms. Firstly, Giles 581g is located at almost exactly the right distance from its red dwarf parent star (Giles 581 )in order to sustain liquid water, which is the only known criterion for organic formation. Planets that orbit too close to or too far away from their stars do not have a suitable climate; this can only be found in a slender strip of solar space around each star known to astronomers as a 'habitable zone'. Around our star—the Sun—Earth is the only planet that occupies this zone, although it nearly stretches to Venus and Mars. Giles 581g is also the right size for organic life. It is about 3.1 to 4.3 times the size of Earth, and this relatively low mass means it should be made mostly of rock. Planets that grow beyond 10 times the size of Earth tend to become gaseous and uninhabitable, without the solid or liquid infrastructure necessary for organisms.
B．Giles 581g is part of a string of planets in the Giles 581 solar system. Two of Giles 581g's siblings—Giles 581e and Giles 581 b—orbit too close to their parent star to support any kind of life on them. Giles 581c skims the near side of the habitable zone, but scientists suggest that it does not have enough of a toehold in this zone to provide a stable infrastructure for organic formations—roughly the same goes for Giles 581d, which has a stronger presence in the habitable zone on its far side, but may not be hot enough for liquid water—opinion is not 'completely settled' on this matter, says James Casting of Pennsylvania State University. Casting, who has studied the two Giles 581 planets on the outer edges of the habitable zone, suggests thatGliese581gis'smack dab in the middle' of the zone which, along with its size and composition, makes it the most exciting and realistic prospect for extra-terrestrial life yet.
C．The comparisons between the Earth and Giles 581g should not be overstated, however. Even if Giles 581 g can sustain organisms, it would be a very different place to live. The main difference is that Giles 581g orbits much closer to its star than the Earth does to the Sun. Because Giles 581 is only one percent as bright as the Sun, it exudes little warmth, and its habitable zone lies much closer than the Sun's. At this closer distance, planets in the zone get locked into strong gravitational pulls that tend to slow their circular movements over time. Eventually, they become stuck with one side constantly facing the star—just as the Moon always shows the Earth the same face. Because of this, it is likely that Giles 581g experiences permanent daytime on the side facing the star and permanent shadow on the other side. It is estimated therefore that average temperatures on the star side would be about 71 degrees C and average temperatures on the other much chillier: -34℃. Nevertheless, Steven Vogt suggests that Giles 581g probably has a comfortable area along the midpoint, known as the terminator. Any life here would always see the star sitting on the horizon and consequently experience eternal sunrise or sunset.
D．Even if there is no life on Giles 581g, its discovery reveals that habitable planets are quite common, with around 10 to 20 percent of red dwarves and sun-like stars boasting them. Giles 581 is one of just nine stars at that particular distance which astronomers have searched with high enough precision to uncover a planet in the habitable zone. While the odds may prove to be slightly lower than 10 percent, the evidence of life—or at least, the high possibility of life—is still overwhelming. There are at least a few hundred billion stars in our galaxy, which means that around 20 to 40 billion planets have the potential for the development of organisms.
E．And so, the search for life continues. Unfortunately, Giles 581g is not particularly amenable to observation. The next step in finding out the chances of life on the planet would be to measure its light spectrum, a process that would reveal molecular oxygen if indeed it exists. The glare from the parent star makes this impossible to do with current instruments, however. Another way to gather information would be to transport a vessel to and from the planet. The technology currently exists to do this, but at 20 light years from earth, it would take 200 years for astronomers to receive the result. Luckily, new information may just be a few years away. Astronomers suggest that many rocky planets are likely to be found in habitable zones during the coming years, and some of these will provide a better platform for research with current instruments.
Reading Passage 2 has five paragraphs, A-E.
Write the correct letter, A-E, in boxes 14-18 on your answer sheet?
A reason why we cannot learn much more about Giles 581g in the near future
Which paragraph contains the following information?
An estimate of the number of planets in habitable zones?
An explanation for why Giles 581g may not rotate?
Giles 581g's location in relation to other planets?
A pre-requisite for the beginning of life?
Complete the diagram below.
Choose the correct letter A-E from the box below.
Write your answers in boxes 19-23 on your answer sheet.?
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