What' s the main topic of this passage?
【正确答案】 A
【答案解析】
单选题 Why air must be pumped into the plane?
【正确答案】 C
【答案解析】
单选题 What would happen if a small part of the plane were to crack?
【正确答案】 B
【答案解析】
单选题 For what purpose does the pilot shut off all the engines?
【正确答案】 A
【答案解析】