been in与enter的区别

Question

China（）the WTO for more than five years.
选项A.has entered B.has been in C.has joined D.has taken part in
答案是B，为什么？

Answer 1

A.has entered 是错误的结构。enter是瞬间动词，不用于现在完成时
B.has been in 说的是“已经加入了”的状态，可用于现在完成时。

供参考。