Retrorocket
n. 制动[减速]火箭系统
🗣️ 情景例句
I started traveling twenty-four hours ago.
从出门到现在已经二十四小时了。
This is a highly controversial subject.
这是一个颇有争议的题目。
we are now pretty certain the Earth is the only one on which life can survive.
我们目前可以肯定的是，地球是生命能存在的唯一行星。