【题目】Three years has passed ever since _____.
A.he has joined the army
B.he joined the army
C.he has been in the army
D.he has been a soldier

【答案】B
【解析】句意：自从他参军时间已经3年了。Join是非延续性动词 be in是延续性动词。此处只是强调过去的事实，故选B。