Do you love cheese? If you do, this new survey will make you happy. According to the survey, cheese is good for teeth and can protect people from getting cavities (蛀牙) . The survey is made by a group of scientists from the Academy of General Dentistry, an organization from the USA. The scientists find that eating cheese can make the mouth’s PH rise. And the higher the mouth’s PH is, the less likely it is that a person gets cavities. That’s why cheese is good for tooth health.
In order to do the survey, the scientists invited 68 children between 12-15 years old to join the test. They tested the mouth’s PH of the children at first. Then they divided the children into three groups. One group of children ate some cheese, another group of children ate sugar-free yoghurt and the last group of children drank a glass of milk. After that, the scientists tested the mouth’s PH of all the children for several times.
The scientists found that the mouth’s PH of the last two groups of children didn’t change, but the mouth’s PH of children from the first group rose greatly. Besides, the scientists also found that cheese could create a protective layer (保护层) on teeth. The layer could protect the teeth from getting hurt by many bad things.
Information Card

The thing that is good for teeth	小题1:___________________
The people who did the survey	小题2:___________________
The people who joined the test	小题3:__________________
The thing that the scientists test	小题4:___________________
The thing that the protective layer can do	小题5:___________________