I am sitting on the cusp of middle age.

我正处于中年。

Men tend to put on weight in middle age.

男人到了中年体重往往会增加。

The master, Mr. Dobbins, had reached middle age with an unsatisfied ambition.

老师，杜宾斯先生已经到了中年，但他追求的目标还没达到。

He is middle age.

他已是中年人。

Most stars on the list are in their middle age.

上榜演员大部分都是中年人。