英语四级阅读理解练习题 第037组

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综合题，请根据题目给出的内容，来回答下面给出的试题。
We all have offensive breath at one time or another. In most cases, offensive breath emanates from
bacteria in the mouth, although there are other, more surprising causes.

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

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 unde, thick layers of mucus (粘液). If
the mouthwash contains alcohol—as most do—it can intensify the problem by drying out the
mouth.


请根据上面给出的内容， 来回答下面的单项选择题（下列每小题备选答案中，只有一个符合题意的正确答
案。每小题0分，共5题 。）
1. The phrase

A ：thrive on
B ：account for
C ：originate from
D ：descend from

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请选择答案： A:B:C:D:
2. Which of the following is mentioned as one of the causes of bad breath?

A ：Tooth trouble.
B ：Sulfur- rich food.
C ：Too much exercise.
D ：Mental strain.

请选择答案： A:B:C:D:
3. According to the passage, alcohol has something to do with bad breath mainly because .

A ：it keeps offending bacteria from reproducing
B ：its smell adds to bad breath
C ：it kills some helpful bacteria
D ：it affects the normal flow of saliva

请选择答案： A:B:C:D:
4. Mouthwashes are not an effective cure for bad breath mainly because .

A ：they can't mask the bad odor long enough
B ：they can't get to all the offending bacteria
C ：their strong smell mixes with bad breath and makes it worse
D ：they can't cover the thick layers of mucus

请选择答案： A:B:C:D:
5. We can infer from this passage that .

A ：offensive breath can't easily be cured
B ：elderly people are less offended by bad breath
C ：heavy drinkers are less affected by bad breath
D ：offensive breath is less affected by alcohol

请选择答案： A:B:C:D:


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