Ques: Read the following article and select the best answer. Article: Cloud seeding is a method of artificially causing clouds to produce precipitation in the form of rain or snow.Cloud seeding has also been used in attempts to modify the severity of hail storms and hurricanes.The effectiveness of cloud seeding remains controversial .but it continues to be used in some regions to try to increase rainfall for agriculture and to build snow packs for water supplies and power production. Cloud seeding was developed by American scientists Irving Langmuir and Vincent Joseph Schaefer during and after World War II.Their work began as an effort to learn more about the buildup of ice on airplane wings, and eventually led them to attempt to create rainfall by releasing several pounds of crushed frozen carbon dioxide into a cloud from an airplane.In this form, the carbon dioxide is called dry ice.On November 13, 1946, the technique appeared to produce snow directly under the cloud; the snow then turned to rain as it fell to the ground. For their experiment, Langmuir and Schaefer selected a supercooled cloud, one in which the water droplets remain liquid in subfreezing temperatures.Their theory was that small grains of dry ice falling through the cloud would cause tiny droplets of water vapor in the cloud to freeze into crystals that attracted more water vapor.Their theory proved to be correct and eventually the crystals became heavy enough to fall from the cloud as snow.As the snow reached the warmer temperatures closer to the ground, it melted and became rain. Another scientist, Bernard Vonnegut, produced a method of cloud seeding using silver iodide .He used particles of silver iodide because its crystal structure resembled that of ice in clouds.Silver iodide also had practical advantages over frozen carbon dioxide It could be stored at room temperature and did not require an airplane as a delivery mechanism.Instead, silver iodide crystals could be fired by cannons high into the air, where wind carried them into the clouds. Question: How many methods of cloud seeding are mentioned in the passage? - three - two - one - four
Ans: two

Ques: Read the following article and select the best answer. Article: They said highly anxious rats which were kept had very low levels of a brain chemical called fibroblast growth factor 2 or FGF2, compared with rats that were more relaxed. But when they improved the anxious rats' living conditions -- giving them new toys to explore and a bigger cage to live in -- levels of this brain chemical increased and they became less anxious. "The levels of this brain chemical increased in response to the experiences that the rats were exposed to. It also decreased their anxiety". Javier Perez of the University of Michigan said in a telephone interview. "It made them behave the same way as the rats that were relaxed", he said. In a former study of people who were severely depressed before they died, the team found the gene that makes FGF2 was producing very low levels of the growth factor, which is known primarily for organizing the brain during development and repairing it after injury. Perez thinks the brain chemical may be a marker for genetic vulnerability to anxiety and depression. But it can also respond to changes in the environment in a positive way, possibly by preserving new brain cells. While both the calm and anxious rats produced the same number of new brain cells, these cells were less likely to survive in the high-anxiety rats, the team found. Giving the rats better living conditions or injecting them with FGF2 helped improve cell survival. "This discovery may pave the way for new, more specific treatments for anxiety that will not be based on sedation , but will instead fight the real cause of the disease," Dr. Pier Vincenzo Piazza from France said in a statement. Question: From the passage we can infer that with the levels of FGF2 decreasing, the rats will _ . - die of anxiety soon - suffer from a headache - become more anxious - become more relaxed
Ans: become more anxious

Ques: Read the following article and select the best answer. Article: Sometimes successful health campaigns can have quite unexpected reactions. The years of warnings about skin cancer mean that Britons are happy to cover themselves in sunscreen or stay out of the sun altogether, but it also means that most of us are not getting enough vitamin D. Scientists announced yesterday that Britons need to increase to three times the amount of vitamin D they get per day. They called on food producers to fortify their products with more of the vitamin and suggested people should consider taking supplements to keep levels up. They also suggested getting out in the sun for short periods more often, but they warned against "sun bingeing". The government does not publish official advice on the amount of vitamin D people should take due to a lack of research, says Dr Birgit Teucher of the Institute for Food Research. But in the US, the government recommends 5 micrograms a day. By that count, Dr Birgit Teucher said that around 90% of Britons between 19 and 64 would be lacking in the vitamin because they only took around 3 micrograms a day. Vitamin D is important for absorption of calcium by the body, which is needed for healthy teeth and bones. A lack of it can lead to serious diseases in both children and adults. The vitamin can be found in some foods but it can also be obtained from chemicals in the skin reacting to sunlight. Dr Barbara Boucher said adults should get 5 to 25 micrograms a day. Shortage of vitamin D may be linked to diseases such as muscle weakness, high blood pressure and rickets . Dr Birgit Teucher gave several reasons for the lack among Britons. Increasing numbers of office-based jobs mean a lack of exposure to the sun; and the rise of becoming overweight means that vitamin D--which is fat soluble is increasingly stored in body fat, where it cannot be accessed readily. Professor Brian Wharton of the Institute of Child Health said that children in particular needed to have enough vitamin D to prevent rickets. Professor Graham Bentham, an environmental scientist at the... Question: From the passage, we can conclude _ . - the babies who were only breast--fed certainly need to take vitamin D supplements - a large quantity of vitamin D stored in body fat is the primary reason for being overweight - the sunlight can produce adequate vitamin D that the body needs all year round - vitamin D is vital for the body to absorb calcium needed for healthy teeth and bones
Ans: vitamin D is vital for the body to absorb calcium needed for healthy teeth and bones

Ques: Read the following article and select the best answer. Article: Shelly Nielsen sees students fall asleep in class at least twice a week. "When I see teens asleep in my class, I wonder if I am really that boring", said Nielsen, a teacher. "I also wonder why they are so tired." Neilson first tried to wake up sleeping students quietly. If the snoozing continues, she may call a student's parents to find out how much sleep the students is getting at night and why. According to a research, teens need at least nine hours of sleep to function properly during the day. And more than 90 percent of teens say they are sleeping less than that each night. "The big problem is the social demand for homework, video games and friends. Teens don't understand how important sleep is." said Dr. Carl Lawyer, a specialist. Rebecca Lucas, another teacher agrees. "Teens are busy," she said, " many activities force them to get home pretty late. When I see teens sleeping in my class, I feel sad. I also feel frustrated because I have so much to teach in such a short amount of time and teens sleeping in the class slows me down." Al Taylor, a teacher says sleeping is not allowed in his class. "When I see a teen sleeping in my class, I feel bad that they didn't get enough sleep but they need to correct it at home," Taylor said. "I've raised teenage boys myself. Teenagers like to wait to the last minute to do their homework so that they often stay up late trying to finish it." Question: What does Shelly first do when she finds students sleeping in class? - She wakes them up with no punishment. - She blames herself for giving a boring lesson. - She asks them to stand outside. - She reports it to their parents.
Ans:
She wakes them up with no punishment.