He' only forty-one years old.要了forty one中间的——为什么还要在year后面加s

前面的数值使year必须用复数形式
=He is a forty-one-year-old man.

forty-one 四十一，这个数词本身就要求有短横，再如：twenty-two 。
注意与：forty-one-yearl-old 是两种用法。比较：
He's only forty-one years old.
He's only a forty-one-year-old man.
希望对你有启发