Read the following article and select the best answer. Article: President Barack Obama rode a bicycle at the White House Science Fair on April 22. But it wasn't an ordinary bike. As he pedaled, the President stayed in place, while the energy from his pedaling powered a water filtration system. He was testing an invention created by a team of 14 students from Northeast High School, in Oakland Park, Florida. Payton Karr, 16, and Kiona Elliot, 18, attended the fair as representatives of the project."We were hoping President Obama would ride the bike, but we didn't actually expect him to," Payton told TFK. " It really meant a lot." Kiona agreed. "It was pretty awesome to see the invention, which was invented by a group of 14 high school students and one teacher, along with the help of community members, got the interest of the leader of our nation," she said. The project was an idea that came about after one of the Northeast students, Kalie Hoke, visited Haiti after the terrible 2010 earthquake and saw how difficult it was to find clean water. The students invented a portable , bicycle-powered emergency water filtration system, which can provide 20-30 people with drinking water in a 15-hour period. The teens hope their invention will one day be used by relief organizations like the Red Cross. " They can take it to places after natural disasters so that water can be clean for the people there," said Payton. Payton and Kiona were among the 100 students from more than 40 states invited to the third annual White House Science Fair, in Washington, D.C., which is also attended by leaders in science and education. President Obama started the event in 2010 to _ students interested in STEM (Science, Technology, Engineering, Maths)."Well, if you're a young person and you produce the best experiment or design, you ought to be recognized for that achievement," Obama said when he first announced the fair. President Obama praised the projects during a speech to attendees after the fair. "The science fair projects of today could become the products and businesses of tomorrow," he said.... Question: The bicycle-powered water filtration system was designed _ . - at the request of the Red Cross - for city families to get pure water - during the terrible 2010 earthquake in Haiti - to provide people in disaster areas with clean water
to provide people in disaster areas with clean water

(Question)
Read the following article and select the best answer. Article: We all know that eating junk food can make us fat. However, a new study suggests that it can do more than that - it can also make us lazy, reported CBS News. In the study, researchers at the University of California, Los Angeles, US divided 32 female rats into two groups. The first group was fed a diet of healthy food such as corn and fish, while the second was given a diet of highly processed food rich in sugar, namely "junk food". Within three months, the rats in the second group were already much fatter than those on the healthy diet. And when researchers trained the rats to do simple tasks, they found even more differences between the two groups rather than weight. During the task - pushing a lever to receive a reward of sugar water - the rats on the junk food diet were found to be less willing to move, and they took longer breaks between each push than the lean rats did. "It is as if the rat is thinking 'This is too much work'," Aaron Blaisdell, leader of the study, told the Los Angeles Times. But what about the possibility that the fat rats were less passionate about getting sugar water because they were already eating lots of sugar in their daily diet? That's why researchers repeated the tests by rewarding fat rats with plain water when they were extremely thirsty. However, the results came out just the same. According to researchers, these differences suggest that junk food changed the chemistry in the rats' brains. The experiment didn't end _ . After six months, the rats' diets were switched, and the overweight rats were given a healthy diet for nine days. However, this change didn't help reduce their weight or improve their ability to perform tasks, which means the effects of their junk food diet persisted . "There's no quick fix," said Blaisdell. For a long time, we've believed that people become fat because they are lazy. But this study has proven the opposite to be true as well, which indicates that laziness and obesity are a "vicious cycle ". So, if you constantly feel tired, lacking any... Question: During the first three months of the experiment by researchers at the University of California, _ . - rats from the healthy diet group ate nothing but corn and fish - rats on the junk food diet ate more than those on healthy diet - rats on the healthy food diet performed better at simple tasks than those on the junk food diet - rats on the junk food diet seemed uninterested in sugary food
(Answer)
rats on the healthy food diet performed better at simple tasks than those on the junk food diet

Ques:Read the following article and select the best answer. Article: Whether it's for a hobby or profession, photography has always been highly valued. Photography has been around for over a hundred years, but what has recently revolutionized it is digital photography. A digital camera looks like a film camera, but it works differently. A digital camera takes pictures or a video by using a CCD sensor instead of film. The data about the images are electronically saved on a flash card. Later on, the flash card can be removed from the camera and put into a card reader. The card reader can be plugged into a computer's USB port. The images and videos can then be saved on a computer for viewing, editing, emailing, or printing. Digital photography received a great deal of criticism in its beginning stages, but with its continued development, it is now capable of producing images of a quality that is similar to. or even better, than that of film photographs. However, what really makes digital photography attractive is its convenience and low cost. Instead of having to go to a lab and waiting to get pictures developed to see what they look like, you can always view the images or-video on the LCD screen that is on the back of the camera. Not only does this feature save time, but it also prevents common mistakes like using a wrong exposure( ) that could ruin an image or video. With the usage of computer programs like Photoshop, more serious photographers can edit their images without the expense of a darkroom. Digital photography is also friendlier to the environment, as harmful chemicals that are needed in the development of film are not used in digital photography. Printing only the best pictures and not having to buy film make digital photography much cheaper. Question: In a digital camera, an image is taken by the camera's _ . - card reader - film - CCD sensor - USB drive

Ans:
CCD sensor