听力题 Conversation one
单选题 Why is the trip to Mars a one-way trip?
【正确答案】 B
【答案解析】
单选题 According to the man, what is more important for those recruits?
【正确答案】 D
【答案解析】
单选题 What is the last part of the conversation about?
【正确答案】 A
【答案解析】