Question

My brother ___(join) the army when he ___ (be) 20 and he ____(be) in it for 5 years

Answer 1

应该是：

joined was has been in
我指纳慧哥在他20岁的时候参的军，现在茄饥他已经入伍5年了。　

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Answer 2

joined
was
have been

这里的when肯定是个点时间，而且肯定是个过去的点时间，咐稿所以用过去时，填joined 和was。
for+一段时间 用现在完成时，终止轿简郑性动词闭颂变成延续性动词。

求采纳～！谢谢
【俊狼猎英】

Answer 3

joined（过去培仔时态举隐）
was（be的过去式）
have been（现在完成时）配答汪

Answer 4

My brother joined___(join) the army when he was___ (be) 20 and he has been____(be) in it for 5 years

Answer 5

joined,was,has been