there have been many changes --- in my hometown in the last ten yeas

问题描述:

there have been many changes --- in my hometown in the last ten yeas
a\ happen
b\ happened
c\ happening
d\ to happen
为什么答案选c
说明理由

这是there be ...doing 的固定句型,译为有.事正在发生.本句用的是现在完成时.这才是正解.欢迎追问,