你们第一次见面是什么时候？

When did you ___first meet each other?

我第一次在收音机上听到这首歌。

I ___first heard the song on the radio.

我第一次在收音机上听说它，然后看到了一份关于它的传单。

I ___first heard of it on the radio and then I saw a leaflet about it.