2014考研英语复习：模拟试题之阅读理解专项练习(二)
Sections III Reading Comprehension
Part A
Each of the passages below is followed by some questions. For each question there are four answers marked A， B， C and D. Read the passage carefully and choose the best answer to each of the questions. Then mark your answer on ANSWER SHEET 1 by blackening the corresponding letter in the brackets with a pencil. (40 points)
Text 1
Say the word bacteria， and most folks conjure up images of a nasty germ like staphylococcus or salmonella that can make you really sick. But most bacteria aren‘t bad for you. In fact， consuming extra amounts of some bacteria can actually promote good health. These beneficial bacteria are available without a prescription in drug and health-food stores and in foods like yogurt. So far， the best results have been seen in the treatment of diarrhea， particularly in children. But researchers are also looking into the possibility that beneficial bacteria may thwart vaginal infections in women， prevent some food allergies in children and lessen symptoms of Crohn’ s disease， a relatively rare but painful gastrointestinal disorder. So where have these good germs been lurking all your life? In your intestines， especially the lower section called the colon， which harbors at least 400 species of bacteria. Which ones you have depends largely on your environment and diet. An abundance of good bacteria in the colon generally crowds out stray bad bacteria in your food. But if the bad outnumber the good-for example， after antibiotic treatment for a sinus or an ear infection， which kills normal intestinal germs as well-the result can be diarrhea. For generations， people have restored the balance by eating yogurt， buttermilk or other products made from fermented milk. But nowadays， you can also down a few pills that contain freeze-dried germs. These preparations are called probiotics to distinguish them from.antibiotics. Unfortunately， you can‘t always be sure that the bacteria in the products you buy are the same strains as those listed on the label or even that they’ re still alive. Probiotics are usually sensitive to both heat and moisture. Among the most promising and most thoroughly researched probiotics is the GG strain of Lactobacillus， discovered by Dr. Sherwood Gorbach and biochemist Barry Goldin， both at Tufts University School of Medicine. L-GG， as it‘ s called， has been used to treat traveler’ s diarrhea and intestinal upsets caused by antibiotics. Even more intriguing， L-GG also seems to work against some viruses， including rotavirus， one of the most common causes of diarrhea in children in the U. S. and around the world. Here the effect is indirect. Somehow L-GG jump-starts the immune system into recognizing the threat posed by the virus. Pediatricians at Johns Hopkins are studying a different bug， the Bb-12 strain of Bifidobacterium， which was discovered by researchers at CHR Hansen Biosystems. Like L-GG， Bb-12 stimulates the immune system. For reasons that are not clear， infants who are breast-fed have large amounts of bifidobacteria in their intestines. They also have fewer intestinal upsets. Dr. Jose Saavedra and colleagues at Hopkins have shown that Bb-12 prevents several types of diarrhea， including that caused by rotavims， in hospitalized infants as young as four months. It has also been used to cure diarrhea in children of all ages.
