请认真阅读下面的短文，按要求回答问题。

When the sun goes down, we can see the moon and the stars high in the sky. We go to sleep, but some people work at night. Doctors and nurses work in the hospital（医院） and help the patients（病人）. Policemen drive police cars to go around the city. They want to keep us safe（安全）. Some workers work in the bakery（烘焙店）. They make nice bread and cakes for breakfast. Some workers carry fruit and vegetables to the supermarkets. Cleaners（保洁员） clean the shops, the schools and the streets at night. Teachers check（批改） students' homework late at night. Taxi drivers drive around and take people to the places they like.