我的祖父在六十多岁时开始学习弹钢琴。

My grandfather started learning to play piano in his ___mid-sixties.

披头士乐队在60年代中期风靡全球。

The Beatles became globally famous in the ___mid-sixties.

今天的气温在60多度，非常适合散步。

The temperature is in the ___mid-sixties today, perfect for a walk.