问题
Great changes ______ in the past few years, anda lot of factories ________.
A:had takenplace have been set up
B:have takenplace have been set up
C:took placehave set up
D:were takenplace were set up
B:have takenplace have been set up
C:took placehave set up
D:were takenplace were set up
正确答案是：
