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The tooth is the hardest part of your body. Your teeth help you in many ways. For example, they can help you talk. They can also help you have a great smile. And the most important job of your teeth is to chew (咀嚼) your food. But do you know how your teeth grow?

When you are born, you don’t have any teeth. About 8 months later, small teeth begin to appear one by one. These teeth are called baby teeth. They are also called milk teeth. You won’t have baby teeth forever. They usually begin to fall out when a child is about 6 years old. Then, permanent (永久的) teeth begin to appear. These teeth are larger and more powerful. Most people will have 28 permanent teeth by the time they are 12 years old.

For some people, four more permanent teeth arrive by their 25th birthday. They are called wisdom teeth (智齿). But these teeth don’t make you smart! Sometimes they bring you pain. If a wisdom tooth brings you too much pain, you should go to a dentist (牙医) and have it pulled out.

1．Which part of your body is the hardest?

A．The nose.

B．The tooth.

C．The leg.

D．The hand.

2．The most important job of your teeth is           .

A．to prepare food

B．to cook food

C．to chew food

D．to protect food

3．What does the underlined word “They” in Paragraph 2 refer to?

A．Baby teeth.

B．Adult teeth.

C．False teeth.

D．Big teeth.

4．How many permanent teeth will most people have by the time they are 12 years old?

A．22.

B．24.

C．26.

D．28.

5．According to the text, what should you do if a wisdom tooth brings you too much pain?

A．Go to a dentist and have it brushed.

B．Go to a dentist and have it pulled out.

C．Go to a dentist and have it cleaned.

D．Go to a dentist and have it examined.