在对话的空白处填上适当的句子，使对话意义完整，语法正确。

A: Maria, have you heard the news on the radio about the space flight to Mars?

B: 1______. Who will take part in it?

A: The astronauts from China, the United States and Russia. 2______. They can travel to space

    and discover something new about Mars. I'd like to be an astronaut when I grow up.

B: It's really cool. However, 3______ and master some basic skills.

A: True. Maria, what are you going to be?

B: Mmm, 4______. Sometimes I want to be a dancer, but I think I'm going to be a scientist in the future.

A: Why? I think you dance very well.

B: Yes, I'd like to perform ballet on the stage in the future. But 5______ .It is my favorite subject in school.

    I believe more and more things will be discovered in the future.

A: That's wonderful! We all need to work hard.