The cause of tooth decay is acid

The cause of tooth decay is acid

Đề bài: 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.

Câu 1: What does this passage mainly discuss?

A.  Good nutrition     

B. Food with fiber

C. Ways to keep your teeth healthy

D. Fluoridization and cavities

Câu 2: The word “it” refers to

A. dental floss 

B. bacteria                  

C. removal of plaque   

D. plaque

Câu 3: According to the passage, all of the following statements about plaque

A. It consists of acid producing bacteria

B. It is not affected by eating sweets

C.  It can be removed from teeth by brushing and flossing

D.  It reduces the positive effect of saliva

Câu 4: 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 whiter       

D. It is a replacement for brushing and flossing in dental care

Câu 5: What can be concluded from the passage about sweets?

A. All sweets should be avoided.

B. Sweets should be eaten with care.

C. It is better to eat sweets a little at a time throughout the day.

D. Sticky sweets are less harmful than other sweets.

Câu 6: The author of the passage states that the amount of acid produced by the bacteria in your saliva increases

A. with the amount of sweets you eat

B. with the number of times you eat sweets

C. if you eat sweets with your meals  

D. if you eat sticky sweets

Câu 7: The word "scrape off" is closest in meaning to

A. repel  

B. rub together with       

C. remove   

D. dissolve

Lời giải:

Đáp án:

1C

2C

3B

4A

5B

6B

7C

Giải thích:

1. Phần này chủ yếu thảo luận về các cách để giữ cho răng của bạn khỏe mạnh.

2. Thông tin: It also makes the surfaces of the teeth more accessible, enabling saliva to neutralize acid and remineralize lesions. (Nó cũng làm cho bề mặt của răng dễ tiếp cận hơn, tạo điều kiện cho nước bọt trung hòa axit và tái khoáng hóa các tổn thương.)

3. Thông tin: 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. (Tốc độ vi khuẩn trong miệng tạo ra axit phụ thuộc vào số lượng mảng bám trên răng, thành phần của hệ vi sinh vật và liệu vi khuẩn của mảng bám có bị "mồi" do tiếp xúc thường xuyên với đường hay không.)

4. Thông tin: 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. (Nếu florua có trong nước uống khi răng đang hình thành, một số florua được tích hợp vào men răng, làm cho răng có khả năng chống lại sự tấn công của axit. Kem đánh răng chứa florua dường như hoạt động theo một cách khác, bằng cách thúc đẩy quá trình tái khoáng hóa các tổn thương sâu răng sớm.)

5. Chúng ta có thể rút ra rằng: Đồ ngọt nên được ăn cẩn thận.

6. Thông tin: The number of times you eat sweets rather than the total amount determines how much harmful acid the bacteria in your saliva produce. (Số lần bạn ăn đồ ngọt chứ không phải tổng số lượng sẽ quyết định lượng axit có hại mà vi khuẩn trong nước bọt của bạn tạo ra.)

7. scrap off = loại bỏ