groundn.地面；地方；根据；主题；立场；水平；背景v.使停飞；困在家中；放在地上；使 ... 搁浅；打基础动词grind的过去式和过去分词形式ground arms放下武器,投降

1. The reflections are recorded by detecting instruments responsive to ground motion.
   反射波由对地面振动极敏感的探测仪器记录下来。