Female birds must sing more melodiously.

那一定是雌鹤叫起来更好听一点。

I wish that I could sing better, more melodiously, but then perhaps you would never have consented to listen to me.

我倒是希望自己能唱得更好一些、更加悦耳一些，不过那样一来你也许永远不会愿意听我唱了。