A-A+
A．How to make a powerful rocket engine.B．How t
问题详情
A．How to make a powerful rocket engine.
B．How to ensure the safety of the crew.
C．How to choose qualified crewmen for the trip.
D．How to enable the spacecraft break free of gravity.
参考答案
正确答案：A
解析：听力中提到，准备登月行动行动时，科学家们面临许多障碍，其中最关键的问题是a rocket engine powerful enough to make the trip，即一个动力足够强大的能够完成旅程的火箭推进器，所以本题的正确答案为A。
