Retrogrades
vi. 逆行（retrograde的第三人称单数形式）
🗣️ 情景例句
A taxi can get you there in less than five minutes.
乘坐的士到那儿不用5分钟。
A man may love his house well without riding on the ridge.
有宝何必人前夸。
It is the natural frequency of emission of the hydrogen atoms in space and was discovered by us in 1951;
这个频率是空间氢原子释放的自然频率，是在1951年被人类发现的。