When my girlfriend rings me out of the blue, I'm in a good mood for the rest of the day.
我突然接到女朋友的电话,接下来的一整天我的心情都很好。
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。