Question

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.

What does this passage mainly discuss?

A. Good nutrition          

B. Food with fiber

C. Ways to keep your teeth healthy  

D. Fluoridization and cavities

Answer 1

Đáp án C

Đoạn văn chủ yếu thảo luận về vấn đề gì?
A. Dinh dưỡng tốt
B. Thức ăn với chất xơ
C. Những cách để giữ răng chắc khỏe
D. Sự cho florua vào nước để ngừa sâu răng và lỗ sâu răng.
Thông tin ở các câu: “To keep your teeth healthy, a regular dental hygiene program should be followed.” (Để giữ cho răng khỏe mạnh, nên tuân theo một quá trình vệ sinh nha khoa thường xuyên.)
“In addition to a regular dental hygiene program, a good way to keep your teeth healthy is to reduce your intake of sweet food.” (Ngoài quá trình vệ sinh răng miệng thường xuyên, cách tốt nhất để giữ cho răng khỏe mạnh 20 răng là giảm lượng thức ăn ngọt.)
Bên cạnh đó xuyên suốt cả đoạn văn bản là các biện pháp bảo vệ răng => Đoạn văn bản này đề cập chủ yếu đến những cách để giữ răng chắc khỏe.