大家帮我看看第三句为什么是错的



. My brother has joined the army for five years.(F)

    My brother has been in the army for five years.(T)

    My brother has been an armyman for ten years.(F)

我觉得第三句也对啊,急啊,好心人帮帮忙

My brother has been an armyman for ten years.

这句话想说想成为一个军人。而has been后不能跟for加一段时间。

To me it sounds vaguely correct too... The only other possibility coud be: 'My brother has been an armyman of ten years.'

... Still, it doesn't sound right either. Perhaps the reason why it's wrong is because there's no such word as 'armyman'...? It ought to be a soldier instead of armyman...?