Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.
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 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.
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 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 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 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. Cavities can be greatly reduced if these rules are followed when eating sweets.
We can infer from the passage that one benefit of fluoride to healthy teeth is __________.
A. It strengthens tooth enamel
B. It stimulates saliva production
C. It makes teeth w
D. It is a replacement for brushing and flossing in dental care
Đáp án A
Chúng ta có thể suy luận từ đoạn văn rằng một lợi ích của florua đối với răng chắc khỏe là __________.
A. Nó tăng cường men răng
B. Nó kích thích sản xuất nước bọt
C. Nó làm cho răng trắng hơn
D. Nó là một chất thay thế cho việc đánh răng và dùng chỉ nha khoa trong chăm sóc răng miệng
Thông tin ở câu: “If fluoride is present in drinking water when teeth are forming, some fluoride is incorporated into the enamel of the teeth, making them more resistant to attack by acid.” (Nếu florua có mặt trong nước uống khi răng đang hình thành, một số florua sẽ được kết hợp vào men răng, giúp chúng có khả năng chống lại sự tấn công của axit.