"几年后"译成英文

few years later

in a few years / in several years / in years
after a few years/after several years/after years
a few years later/ several years later/ years later

几年可以用a few / several 来修饰，也可以不要修饰，直接用years；

而这个介词也有多种，具体看使用的背景，如：
·He may be a well-known scholar in this field in (a few/several) years. 几年后他可能会成为这个领域知名的学者。 表示将来的“几年后”用in；
·He became a well-known scholar in this field after (a few/several) years. 几年后他成了这个领域知名的学者。 表示已经过去的“几年后”用after；
·(A few/Several) Years later, he became a well-known scholar in this field. 意思同上一句。later短语可与after短语互换，但later短语常用于句首/中，也有用于句末的。

in a few years

a few years later
After a few/several years
两者都可,要视具体语境,才能挑出最合适的

after several years

a few years later