Read the following passage and mark the letter A, B, C, or D to indicate the correct word for each of the blanks.
BIRD FLU
There has been a(n) (41) ___________ of avian influenza, better known as bird flu in Asia recently. The first (42) ___________ died
two weeks ago in Vietnam and there have been cases reported since in Thailand, and there are some suspected cases in Cambodia (43) ___________.
Wild birds are affected by a large number of flu viruses, just as humans and other animals (44) ___________, but they are normally exclusive to birds. If the viruses manage to mutate, they can jump the species barrier and infect human beings. The first case (45) ___________ someone died was in Hong Kong in 1997.
There are several different forms of bird flu, raging from mild to very (46) ___________ infections, which spread rapidly and kill many of the birds they infect. It is spread by (47) ___________ birds-ducks, in particular - which carry the virus, but aren't killed by it. They can spread the virus to farm birds through (48) ___________ contact or by contaminating water supplies.
World Health Organization officials have attributed the spread of bird flu to human contact with the droppings of infected birds and (49) ___________ sanitation. There was no evidence at first that the virus spread from person to person, though there has been a (50) ___________ of this happening being investigated by scientists.
Read the following passage and mark the letter A, B, C, or D to indicate the correct answer
ACID DUST
Calcite-containing dust particles blow into the air and combine with nitric acid in polluted air from factories to form an entirely new particle-calcium nitrate. These nitrates have optical and chemical properties that are completely different from those of the originally dry dust particles. Due to this, climate models need to be updated to reflect this chemistry. Calcite dust is common in arid areas such as Israel, where this past winter scientists collected particles for analysis.
Working from a mountaintop, the team collected dust that had blown in from the northern shores of Egypt, Sinai, and southern Israel. The particles had combined with air containing pollutants that came from Cairo. They analyzed nearly 2,000 individual particles and observed the physical and chemical changes at the W.R Wiley Environmental Molecular Sciences Laboratory.
An important change in the properties of the newly formed nitrate particles is that they absorb water and retain moisture. These particles can scatter and absorb sunlight-presenting climate modelers, who need to know where the energy is going, a new wild card to deal with. Other studies of dust samples from the Sahara and the Saudi Arabian coast and loess from China show that the higher the calcium in the mineral, the more reactive they are with nitric acid. In fact, once the particle is changed, it stays that way.
Read the following passage and mark the letter A, B, C, or D to indicate the correct answer.
Aging is the process of growing old. It occurs eventually in every living thing provided, of course, that an illness or accident does not kill it prematurely. The most familiar outward signs of aging may be seen in old people, such as the graying of the hair and the wrinkling of the skin. Signs of aging in a pet dog or cat include loss of playfulness and energy, a decline in hearing and eyesight, or even a slight graying of the coat. Plants age too, but the signs are much harder to detect.
Most body parts grow bigger and stronger, and function more efficiently during childhood. They reach their peak at the time of maturity, or early adulthood. After that, they begin to decline. Bones, for example, gradually become lighter and more brittle. In the aged, the joints between the bones also become rigid and more inflexible. This can make moving very painful.
All the major organs of the body show signs of aging. The brain, for example, works less efficiently, and even gets smaller in size. Thinking processes of all sorts are slowed down. Old people often have trouble in remembering recent events.
One of the most serious changes of old age occurs in the arteries, the blood vessels that lead from the heart. They become thickened and constricted, allowing less blood to flow to the rest of body. This condition accounts, directly or indirectly, for many of the diseases of the aged. It may, for example, result in heart attack.
Aging is not a uniform process. Different parts of the body wear out at different rates. There are great differences among people in their rate of aging. Even the cells of the body differ in the way they age. The majority of cells are capable of reproducing themselves many times during the course of a lifetime. Nerve cells and muscle fibers can never be replaced once they wear out.
Gerontologists - scientists who study the process of aging-believe this wearing out of the body is controlled by a built-in biological time-clock. They are trying to discover how this clock works so that they can slow down the process. This could give man a longer life and a great number of productive years.