She's middle-aged./她已到中年了。

A: Your mother is very young.

A: 你的母亲很年轻。

B: No, she's not. She's middle-aged.

B: 不，她不年轻了。她已到中年了。

A: Middle-aged? She's only about 40.

A: 中年？她才40岁上下。

B: 40 is middle-aged. 40 is old!

B: 40岁就是中年。40岁的人老了！

A: 40 is not old! Wait till you're 40.

A: 40并不老！等你到40岁就知道了。

B: I never want to be middle-aged.

B: 我永远也不想到中年。

Notes 注释

1. Another way of describing people is by age. People can be young, middle-aged, or old. People don't see age in the same way, however:
描述某人的另一种方法是通过年龄。人有年轻的、中年的或者老年的，但是人们看待年轻的方式不一样: Your mother is very young. (你的母亲很年轻。) No, she's not. (不，她不年轻了。)

2. Young people want to remain young: I never want to be middle-aged.
年轻人希望保持年轻: I never want to be middle-aged. (我永远也不想到中年。)