Lǎoshī / yòng / guànxìngxì / jiěshì / le / wèishénme / xíngxīng / huì / yánzhe / tèdìng / guǐdào / yùnxíng

老师用惯性系解释了为什么行星会沿着特定轨道运行。

The teacher used an inertial frame to explain why planets move along specific orbits.