Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

How might volunteering contribute to lower blood pressure? Performing volunteer work could increase physical activity among people who aren’t otherwise very active, says lead study author Rodlescia Sneed, a doctoral candidate in social and health psychology at Carnegie Mellon University. It may also reduce stress. “Many people find volunteer work to be helpful with respect to stress reduction, and we know        that stress is very strongly linked to health outcomes,” she says. As with any activity thought to improve health, researchers are trying to identify the specific characteristics of volunteering that provide the greatest benefit. For example, how much time would you need to put into volunteer work to lower your blood pressure or live longer? In the Carnegie Mellon study, 200 hours of volunteering per year correlated to lower blood pressure. Other studies have found a health benefit from as little as 100 hours of volunteering a year. Which types of volunteer activities improve health the most? No one really knows. Sneed speculates that mentally stimulating activities, like tutoring or reading, might be helpful for maintaining memory and thinking skills, while “activities that promote physical activity would be helpful with respect to cardiovascular health, but no studies have really explored this.” One key for deriving health benefits from volunteering is to do it for the right reasons. A 2012 study in the journal Health Psychology found that participants who volunteered with some regularity lived longer, but only if their intentions were truly altruistic. In other words, they had to be volunteering to help others not to make        them selves feel better.

The Greek philosopher Aristotle once surmised that the essence of life is “To serve others and do good.” If recent research is any indication, serving others might also be the essence of good health.

The word “It” in paragraph 2 refers to________.

A. Physical activity

B. Blood pressure 

C. Doctoral candidate 

D. Volunteer work

Read the following passage and mark the letter A, B, tr or I) to indicate the correct answer to each of the questions from 36 to 42.

     Humans have struggled against weeds since the beginnings of agriculture. Marring our gardens is one of the milder effects of weeds - any plants that thrive where they are unwanted. They clog waterways, destroy wildlife habitats, and impede fanning. Their spread eliminates grazing areas and accounts for one-third of all crop loss. They compete for sunlight, nutrients, and water with useful plants.

     The global need for weed control had been answered mainly by the chemical industry. Its herbicides are effective and sometimes necessary, but some pose serious problems, particularly if misused. Toxic compounds threaten animal and public health when they accumulate in food plants, groundwater, and drinking water. They also harm workers who apply them.

     In recent years, the chemical industry has introduced several herbicides that are more ecologically sound. Yet new chemicals alone cannot solve the world's weed problems. Hence, scientists are exploring the innate weed-killing powers of living organisms, primarily insects and microorganisms.

     The biological agents now in use are environmentally benign and are harmless to humans. They can be chosen for their ability to attack selected targets and leave crops and other plants untouched. In contrast, some of the most effective chemicals kill virtually all the plants they come in contact with, sparing only those that are naturally resistant or have been genetically modified for resistance. Furthermore, a number of biological agents can be administered only once, after which no added applications are needed. Chemicals typically must be used several times per growing season.

Which of the following is NOT given as an advantage of using biological agents over chemical herbicides?

A. They are safer for workers

B. They are less likely to destroy desirable plants

C. They are more easily available

D. They do not have to be used as often

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 38 to 42.

  Lead poisoning in children is a major health concern. Both low and high doses of paint can have serious effects. Children exposed to high doses of lead often suffer permanent nerve damage, mental retardation, blindness, and even death. Low doses of lead can lead to mild mental retardation, short attention spans, distractibility, poor academic performance, and behavioral problems.

  This is not a new concern. As early as 1904, lead poisoning in children was linked to lead-based paint. Microscopic lead particles from paint are absorbed into the bloodstream when children ingest flakes of chipped paint,plaster,or paint dust from sanding. Lead can also enter the body through household dust, nailbiting, thumb sucking, or chewing on toys and other objects painted with lead-based paint. Although American paint companies today must comply with strict regulations regarding the amount of lead used in their paint, this source of lead poisoning is still the most common and most dangerous. Children living in older, dilapidated houses are particularly at risk.

The word "dilapidated" is closest in meaning to which of the following?

A. unpainted

B. decorated

C. broken down

D. poorly painted

Tính giá trị của biểu thức: 

(-55).(-25).(-x) với x = 8

Cho hai tập hợp A = {m,n,p,q} và B = {m,p}. Dùng kí hiệu ⊂  để thể hiện mối quan hệ giữa hai tập hợp A và B

Cho luồng khí CO dư qua hỗn hợp các oxit CuO, FeO, Al 2 O 3 , MgO nung ở nhiệt độ cao. Sau phản ứng hỗn hợp chất gồm

A. Cu, Fe, Al, MgO

B. Cu, Fe, Al 2 O 3 , MgO

C. Cu, Fe,  Al 2 O 3 , Mg

D. Cu, FeO,  Al 2 O 3 , MgO

Viết các phép chia sau dưới dạng phân số:

a) 2:3;

b) 3: (-4);

c) - 3:8;

d) (-l):(-3).

Kết quả của phép tính 71 + 50 + 29 là:

A. 150

B. 140

C. 160

D. 105

Một phân tử ADN mạch kép có 20% số nucleotit loại A. Theo lí thuyết, tỉ lê nucleotit loại G của phân tử này là:

A. 40% 

B. 10% 

C. 30% 

D. 20%

Find the word which has a different stress pattern from the other.

A. describe

B. enter

C. agree

D. replace