From the passage we may infer that______.

A．positive B．negative C．hostile D．appreciative

Until a few years ago, the most doctors could do was to counsel patients with bad breath about oral cleanliness. Now they are finding new ways to treat the usually curable condition. Bad breath can happen whenever the normal flow of saliva (唾液) slows. Our mouths are full of bacteria feeding on protein in bits of food and shed tissue. The bacteria emit evil smelling gases, the worst of which is hydrogen sulfide (硫 化物). Mouth bacteria thrive in airless conditions. Oxygen rich saliva keeps their numbers down. When we sleep, for example, the saliva stream slows, and sulfur producing bacteria gain the upper hand, producing classic “morning breath”. Alcohol hunger, too much talking, breathing through the mouth during exercise anything that dries the mouth produces bad breath. So can stress, though it’s not understood why. Some people’s breath turns sour every time they go on a job interview. Saliva flow gradually slows with age, which explains why the elderly have more bad breath trouble than younger people do. Babies, however, who make plenty of saliva and whose mouths contain relatively few bacteria have characteristically sweet breath. For most of us, the simple, dry mouth variety of bad breath is easily cured. Eating or drinking starts saliva and sweeps away many of the bacteria. Breakfast often stops morning breath. Those with chronic dry mouth find that it helps to keep gum, hard candy, or a bottle of water or juice around. Brushing the teeth wipes out dry mouth bad breath because it clears away many of the offending bacteria. Surprisingly, one thing that rarely works is mouthwash. The liquid can mask bad breath odor with its own smell, but the effect lasts no more than an hour. Some mouthwashes claim to kill the bacteria responsible for bad breath. The trouble is, they don’t necessarily reach all offending germs. Most bacteria are well protected from mouthwash under thick layers of mucus (粘液). If the mouthwash contains alcohol-as most do-it can intensify the problem by drying out the mouth. 第31题：The phrase “emanate from” in Paragraph 1 most probably means “________”. A) thrive on B) account for C) originate from D) descend from

A．study the fish in the aquarium B．decide which fish to put in the aquarium C．supervise the building of the aquarium D．help build the aquarium

A.consumers are the only factor to determine what shall be produced B.how goods and services are produced is mainly conducted by the profit mottve C.the American economic system is exactly a market-oriented economy D.businessmen can produce more goods Ln order to earn more profits

A．True B．False P C．Not mentioned

A. It continued its escalating trajectory. B. The median CEO pay was over $10 million. C. Many board members regarded CEO's pay moderate. D. Board members took some measures to deal with CEO's high pay.

A．humans, worms and rodents are different. B．most people are not willing to be put on a strict diet. C．the effect is not known. D．genetic changes in tissues can not be performed on humans.

A．preferred literature to linguistics. B．used to live in the outskirts of the city. C．didn't like reading writers like Updike. D．didn't get along well with her roommates.

A．are equally kind and optimistic as their bosses B．appreciate and feel encouraged by the benefits package C．can't escape the unpleasant competition for power in the office D．are far away from office competition thanks to the innovation in managing

A．low temperatures are created by using a house B．the house is made green in order to keep heat C．heat is prevented from escaping outside D．everything is kept green in a house

A. controversial proposals Can be found only among the presidential nominees． B. using pupils’test scores to identify ineffective teachers has been widely accepted． C. both Democratic presidential nominees support the idea of accountability． D. neither the Republican ilor the Democratic presidential nominees favor NCLB．

A.test his endurance B.prove his self-sufficiency C.experience adventure D.respond to new experiences

A.two million B.300，000 C.480 times 300，000 D.400，000

A．is much better than any other robots. B．is no more than a mechanic device. C．may be put into mass production. D．may have some practical value.

A．most of the gifted children became white collars. B．Half of the gifted followed up graduated from all colleges. C．Each of the talented published at least one article. D．Bright men got higher income than bright women.

A．the coast was straight and unobstructed B．ships there had high masts C．coastal waters were safe D．the lighthouses were built on high places

A．women were not willing to go out for work in the past. B．families ate lunch at a fixed time at home. C．most of the vegetables people ate were produced by themselves. D．foods sold in the grocer's shop were rare and fresh.

A．excavators have been replaced by specialist analysers. B．research design comes into being with changes in archaeology. C．field work in the past possesses a strategic nature. D．processual archaeology makes excavation lose its function.

A．a subject-centered view of education B．a student-centered view of education C．a teacher-centered view of education D．a practice-centered view of education