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Reading comprehension -TOEFL- Lesson 157 (Đọc hiểu -TOEFL- Lesson 157)

Reading and answers the question: The cause of tooth decay is acid, which is produced by bacteria in
the mouth. The acid removes minerals from tooth enamel, allowing
tooth decay to begin; the saliva in your mouth encourages remineralization
and neutralizes the acid. The rate at which bacteria in the mouth
5 produce acid depends on the amount of plaque on the teeth, the composition
of the microbial flora, and whether the bacteria of the plaque have
been "primed" by frequent exposure to sugar. To keep your teeth healthy,
a regular dental hygiene program should be followed.

10 Removing plaque with a toothbrush and dental floss temporarily reduces
the numbers of bacteria in the mouth and thus reduces tooth decay.
It also makes the surfaces of the teeth more accessible, enabling
saliva to neutralize acid and remineralize lesions. If fluoride is
present in drinking water when teeth are forming, some fluoride is
15 incorporated into the enamel of the teeth, making them more resistant
to attack by acid. Fluoride toothpaste seems to act in another way,
by promoting the remineralization of early carious lesions.

In addition to a regular dental hygiene program, a good way to keep
20 your teeth healthy is to reduce your intake of sweet food. The least
cavity-causing way to eat sweets is to have them with meals and not
between. The number of times you eat sweets rather than the total
amount determines how much harmful acid the bacteria in your saliva
produce. But the amount of sweets influences the quality of your
25 saliva. Avoid, if you can, sticky sweets that stay in your mouth
a long time. Also try to brush and floss your teeth after eating
sugary foods. Even rinsing your mouth with water is effective. Whenever
possible, eat foods with fiber, such as raw carrot sticks, apples,
celery sticks, etc., that scrape off plaque, acting as a toothbrush.
30 Cavities can be greatly reduced if these rules are followed when
eating sweets.1. What does this passage mainly discuss?

2. According to the passage, all of the following statements about plaque are true EXCEPT

3. We can infer from the passage that one benefit of fluoride to healthy teeth is

4. The word "it" in line 12 refers to

5. What can be concluded from the passage about sweets?

6. The word "scrape off" in line 29 is closest in meaning to

7. It can be inferred from the passage that foods with fiber are

8. According to the passage, the value of eating foods with fiber is that

9. The author of the passage states that the amount of acid produced by the bacteria in your saliva increases

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