1. five
2. eight
3. 
Duong:    Hello, Gabriela.
Gabriela: Hi, Duong.
Duong:    How many students are in your class?
Gabriela: I think there are nine.
4.
Duong:    My class is bigger.
Gabriela: Really? How many?
Duong:    We have 19 students.
5. 
Duong:    Maybe my class is bigger
           because it is shorter.
Gabriela: How long is your class?
Duong:    It is two hours a day.
6. 
Gabriela: Is that all?
Duong:    Yes, that’s all.