阅读理解。 When he was young, Dave wanted to be a policeman, but when he was 18, he decided to be a dentist,because dentists earn more money than policemen. To become a dentist, Dave had to spend five years at university and take a lot of exams. In his job, Dave has to clean and repair people's teeth, and sometimes he has to pull them out! He doesn't have to get up very early but he has to work hard, usually from 10:00 in the morning to 7: 30 in the evening, from Monday to Saturday. He likes his job because he never has to take his work home, and he meets lots of people. One thing he doesn't like is that he can't really talk to his patients, because he is working inside their mouths! 根据短文内容，补全下列句子（每空一词）。 l. To become a ________ was Dave's dream when he was a child. 2. Dave studied at university for five years to become a _________. 3. In Dave's job, he has to clean and ________ people's teeth. 4. Dave works ________ from Monday to Saturday. 5. Dave can't really talk to his ________ when he is working.