51. (2018厦门)—It's the second time I came to Xiamen. It ________ a lot.
—Yes, it's more and more beautiful.
A. was changing  B. has changed  C. will change
51. B【解析】考查现在完成时。句意“这是我第二次来厦门。它已经改变了许多。”“是的，它越来越漂亮了。”此处表达：厦门已经变化了很多。用现在完成时，故选B。