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?

It _________ that many people are homeless after the floods.

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Sandara has not rarely missed a play or concert since she was seventeen years old.

Mark the letter A, B, C, D on your answer sheet to indicate the word whose underlined part differs from that of the other three in pronunciation in each of the following questions:

Mark the letter A,B, C or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

I had to clear the spare room before I could start decorating.

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Works are written by Vladimir Nabokov often contain heroes and heroines who have lived in many places.

Different conservation efforts _________ in order to save endangered species.

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He didn’t pay attention to what I said.

I think the strikes will bring _________ some changes in management.

The brain is made up of billions of neurons that differ _________ each other greatly _________ size and shape.

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The education system is a mirror that reflects the culture.

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Mostly medical doctors have had some training in psychology and psychiatry.

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It is an occasion when strength and sports are tested, friendship and solidarity was built and deepened.

Peter: “Do you like going to the cinema this evening, Susan?”
Susan: “_______.”

When we were in Athens, I bought a _________ statuette.

More and more people were moving to Glasgow as they found it _________ to earn a living there