Scientists from a London university say we clean our teeth the wrong way. Researchers found that different dentists give us different advice. The researchers looked at advice in dental textbooks, toothpaste instructions and clinics. They found five basic ways of tooth-brushing and said all of them were incorrect. Most of the methods are about moving the toothbrush along the teeth, with small movements. The researchers said we should stop doing this. They said we should use a backwards and forwards movement instead. 

    The lead author of the study is a professor of dental public health. He said we need good information on the best way to brush our teeth. The research suggests not brushing teeth more than twice a day. This damages the enamel on the teeth. We should brush for no longer than three minutes each time. We shouldn't use too much pressure and brush our teeth too hard. Researchers also said we shouldn't clean our teeth immediately after eating. This is when strong acid in your mouth can damage teeth. We should also clean our tongue because it has a lot of bacteria. 

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1.Scientists say we clean our____________the wrong way.

A faces

B teeth

C hands

D hair

解析：选B。B 细节理解题。根据第1段第1句Scientists from a London university say we clean our teeth the wrong way.可知，故选B。

2.The incorrect ways of tooth-brushing are from the following EXCEPT____________.

A dental textbooks

B tooth paste instructions

C clinics

D researchers

解析：选D。D 综合理解题。根据第1段内容可知牙科医生、牙膏说明书与牙科诊所所给的刷牙方式可能都是错的，并未提到研究者（researchers）给的刷牙方式是错，故选D。

3.The research advises us not to brush our teeth___________a day.

A more than twice

B less than twice

C more than three times

D once

解析：选A。A 细节理解题。根据第2段第3句The research suggests not brushing teeth more than twice a day.可知，故选A。

4.Which could be OK to brush our teeth each time?

A 5 minutes.

B 3 minutes.

C 5 seconds.

D 3 seconds.

解析：选B。B 判断推理题。根据第2段第5句We should brush for no longer than three minutes each time.可知，故选B。

5.What’s the best title for the passage?

A Right ways to brush our teeth

B Keep your teeth clean

C Doctors are not always right

D An apple a day keep doctors away

解析：选A。A 文章标题题。A项“正确的刷牙方式”契合文章主旨，故选A。