一道初中英文语法题.Anumberofmajorartexhibitionsareheldatthemuseumovertheyears.为什么不能把areheld换成washeld或者hasbeenheld呢?请解释一下!谢谢了!^^

Question

一道初中英文语法题.
A number of major art exhibitions are held at the museum over the years .
为什么不能把 are held 换成was held 或者has been held呢?
请解释一下!谢谢了! ^^

Answer 1

over the years 表示近几年,是现在完成时态的标志
我认为这句话应该用 have been held 而不是 are held