Question

in his sixties意思是他六十多岁,那有没有in the sixties

Answer 1

有,意思是“在60年代的时候”或“在六十多岁的时候”.

至于具体指是在哪个世纪60年代的时候/在谁的六十多岁的时候,则需要根据上下文具体判断.

如：Do you know of someone whose age is in the sixtieth?

It happened in the sixties.

那事发生在六十年代.

In the sixties,rock and roll was the spirit of the time.

在60年代,摇滚是那个时代的灵魂.

There are fewer longhairs around here than there were in the sixties.

这附近的嬉皮士现在60年代少多了.