A study shows that people have more gum disease today than they did 2,000 years ago. The study, from London's King's College, is now in the British Dental Journal（英国牙科杂志）. Researchers looked at the teeth of 303 people who lived 2,200-2,400 years ago. They were from head bones found at an old tomb in England. The researchers said only 5 per cent of the bones had gum disease. Up to 30 per cent of people today have gum disease. Professor Francis Hughes was surprised because people did not have toothbrushes or toothpaste back then. They also did not visit dentists, like we do today. 

    Smoking is the main reason why people have gum disease today. The study shows that our oral health has become worse over the past 2,000 years. Gum disease could start going down if more people stop smoking. A researcher said: "As smoking declines…we should see a decline in the numbers of people with the disease." Gum disease is because bacteria build up in your mouth. The bacteria attack your gums and can make your teeth fall out. People can lower the risk of gum disease by regular brushing, using mouthwash and not smoking. 

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1.Who shall we go for help if we have gum disease?

A Dentists.

B Police.

C Teachers.

D Drivers.

解析：选A。A 判断推理题。有了齿龈病自然是选择看牙医，故选A。

2.What is the main reason of gum disease today?

A Smoking.

B Drinking.

C Drugs.

D Rice.

解析：选A。A 细节理解题。根据第2段第1句Smoking is the main reason why people have gum disease today.可知，故选A。

3.Which statement is RIGHT according to the passage?

A Researchers looked at 303 people who died in World War I.

B There was no gum disease 2000 years ago.

C Our oral health has become worse over the past 200 years.

D Gum disease can go down if we don’t smoke.

解析：选D。D 内容理解题。根据第2段第三句Gum disease could start going down if more people stop smoking.可知，故选D。

4.Which can NOT lower the risk of gum disease?

A Regular brushing.

B Mouthwash.

C Not smoking.

D Bacteria.

解析：选D。D 内容理解题。细菌（bacteria）只会引起或加重齿龈病，不会降低患齿龈病的风险，故选D。