听力原文：

M: Hey, Maria, where are you going?  

W: I’m going to the dentist this afternoon.   

M: What’s the matter with you?  

W: Nothing much. I only want to have my teeth cleaned.   

M: Really? My teeth always hurt after the dentist cleans them.   

W: How often do you go to the dentist, Jack?

M: Once every two years.   

W: Well, you should go every six months.  

M: I know. But my teeth hurt after I see the dentist.   

W: Because you don’t often see the dentist. 

M: But I brush my teeth every day.

W: Only brushing your teeth isn’t enough.  

M: OK. Who’s your dentist?  

W: Dr. Johnson. He’s really a good dentist.   

M: Do you have his phone number? I’ll call him. 

W: Yes. I’ll give you his phone number later.

Question: How often does Jack go to the dentist?

参考答案： 

Once every two years.