一般来讲是join the army 还是 join army 还是join an army

一般来讲是join the army 还是 join army 还是join an army 是join in army还是 join in a army? 是join the army（陆军）还是take part in army（陆军）? serve in the army和join the army的区别 join the army.这个词组中army是否需要大写. Only after---reached eighteen---join the army. How long before did he join the army?改错. It is ten years since he ____(join) the army my brother is __ to join the army. join in the army里的in为什么要去掉 How long before did he join the army?改错 my brother is ______ to join the army.