回答与草原生态系统相关的问题；

为缓解旱情，实施人工降雨．飞机在高空投撒干冰（固态二氧化碳），干冰进入冷云层，就很快 ____成气体，并从周围吸收大量的热，使空气的温度急剧下降，空中的水蒸气便 ____成小冰粒，这些冰粒逐渐变大而下降，遇到暖气流便 ____为雨点降落到地面．

补全对话(选择)。

A: Hello. Zhang Yu! ____

B: I'm reading a newspaper.

A: ____

B: Yes. There is a report about Zhou Yang.

A: ____

B: She is a player in China female short track speed skating team. ____

A: When and where was she born?

B: ____

A: Do you want to be a famous person like her when you grow up?

B: Aha, of course. So I have to work hard at school.

A: Well. You're a good student.

B: Thank you!

A. Who is Zhou Yang?

B. What's your hobby?

C. She was born in Jilin Province on June 9^th, 1991.

D. What are you doing now?

E. She won the gold medal in the 2014 Winter Olympic Games in Sochi.

F. How do we succeed in life? Is she from China?

G. Is there anything new on it?

亚洲与北美洲的分界线、俄罗斯与美国的国界线和国际日期变更线“三线”穿过的海峡是 (     )