They felt ---- at the ---- rocket.

答案是C
amazing使人感到惊讶的,形容一种现象,事情
amazed感到惊讶的,形容人的感受
一般－ed结尾的都是以人做主语,解释为感到***,－ing结尾以物做主语,表示令人感到***
比如：interesting,this question is interesting,这道题目令人觉得有趣
interested,I am very interested in this issue,对于这个问题我深感有趣