The expression "a thirst for knowledge" may soon have a new meaning for millions of people who have no way to get clean water. Researchers have developed a book with specially treated pages that can turn dirty water into clean and drinkable water. They say their invention could improve the lives of many in the developing world. About 700 million people around the world are at risk of disease or even death because their drinking water is not clean. The water is polluted by harmful bacteria. The book contains 25 pages. Each page is about one millimeter thick. The pages contain very small particles   of silver. The pages can be used as filters to remove harmful microorganisms   that can pollute drinking water. The filter kills the organisms that pass through it. Pictures on the pages show the dangers of dirty water and how to use the book for those unable to read. The pages are made of filter paper. They are designed to be torn from the book. Water can be poured through the paper to be cleaned. Ms. Dankovich, the inventor, says each page can treat up to 100 liters of water. She recently presented her invention at the meeting of the American Chemical Society in Boston, Massachusetts. She was asked whether she had considered adding classic literature on the book's pages. "The idea of classic texts--that's of interest maybe later. We have discussed a little bit more exciting text. But we really haven't had the time to go through _ " she says. Teri Dankovich and another researcher tested the drinkable book in Bangladesh, Ghana and South Africa. The tests proved to be successful. Water for Life, a non-governmental organization, has provided financial support for the project. In which country did not the researchers test the drinkable book? A) Bangladesh. B) Ghana C) South Africa. D) America.
D

Plants need green leaves to make food. A plant needs sunlight and carbon dioxide  from the air for making food and it also needs water and salts from the soil to make food too. There are certain cells   in the leaves which change carbon dioxide and water into sugar. To do this the cells needs energy, which they get from the sunlight. Green leaves make food for the whole plant. A red leaf can make food too because under the red color1ing of the leaf there are food----making cells. There are no leaves which are completely yellow, for they can't make food. The plant makes sugar for its food. In sunlight green leaves make a lot of sugar. The veins   can't carry all this sugar away, so the leaves change the sugar into starch  , which is kept and so stored in the leaves. At night, the starch changes back to sugar. It is then carried away from the leaves. Some of the sugar is used as food by the plant while the rest is stored as starch. In some plants, food is stored in the roots, in others it is stored in the stem   and in leaves, fruits and seeds. The cells in the green leaves can get the most energy when   _  . A) it is daytime B) it is night C) it is sunny D) it is rainy
C

It had been a difficult move. I'd left my family and friends in Indiana, the beloved state where I'd lived most of my life. My new home in Florida was thousands of miles away from anything I knew. It was hot--all the time. Jobs were hard to come by, but I was up for almost any challenge. At last, I taught in a special school where students have severe learning and behavioral difficulties. Another teacher and I had spent weeks teaching the children appropriate behavior for public outings. Unexpectedly, only a few students, including Kyle, had not earned the privilege of going. He was determined to make his disappointment known. In the corridor  between classrooms, he began screaming, cursing, spitting, and swinging at anything within striking distance. Once his outburst died down, he did what he'd done when he was angry at all his other schools, at home, even once at a juvenile detention center. He ran. People watched in disbelief as Kyle dashed straight into the heavy morning traffic in front of the school. I heard someone shout, "Call the police!" But I ran after him. Kyle was at least a foot taller than me. And he was fast. His older brothers were track stars at the nearby high school. But I could run long distances without tiring. I would at least be able to keep him in my sight and know he was alive. After several blocks of running directly into oncoming traffic, Kyle slowed his pace. He took a sharp left. Standing next to a trash bin, Kyle bent over with his hands on his knees. I must have looked ridiculous. But his was not a look of fear. I saw his body relax. He did not attempt to run again. Kyle stood still and watched me approach. I had no idea what I was going to say or do, but I kept walking closer. He opened his mouth to speak when a police car pulled up, abruptly filling the space between Kyle and me. The school principal and an officer got out. They spoke calmly to Kyle, who willingly climbed into the back of the vehicle. I couldn't hear what was said, but I didn't take my eyes off Kyle's face,... From the passage we know that   _  . A) the author left her family to Florida because jobs were hard to come by in Indiana. B) students were allowed to go out after they passed some specific tests. C) the author worked in a school where students were excellent. D) no teacher had ever run after Kyle before except the author .
D

Losing a baby tooth can be fun for a kid. You can put it under your pillow and look forward to finding some money there in the morning. And then you can watch your new permanent  tooth grow in its place. But if a permanent tooth falls out, that's a problem. There isn't another one under the gum that can replace it. Unfortunately, this happens to some older people. And if permanent teeth fall out-or need to be pulled-an older person might need dentures. Dentures, known as false teeth, are a set of replacement teeth for any teeth that are missing. There are partial dentures, which take the place of only a few teeth and prevent the others from changing position. If all the teeth are gone, the person would need complete dentures, which replace every tooth in the mouth. Dentures can cause pains at first and take little time to get adjusted to. They also need special care. They should be brushed daily with a special denture brush and cleanser and soaked in denture solution when not in the mouth. Dentures are important for older folks because, without teeth, it's hard to smile, talk, and eat properly. But it can be a little  _ if you see someone take out his or her dentures. It can also be strange to see someone, like a grandparent, without dentures in because he or she won't have any teeth. Try not to make fun of the person because this could cause hurt feelings. People usually lose their permanent teeth due to periodontal disease, or gum disease, which is caused by bacteria that attacks the gums. Diseased gums aren't strong and healthy, so teeth can get loose and fall out. Older people often have many cavities that have been filled over the years, and these fillings can weaken over time, leading to more tooth decay. If one of your baby teeth falls out, you_. A) should have a false tooth fixed in its place B) have to put it under your pillow at once C) will gain a permanent tooth in future D) can exchange it for some money

C