Great changes ______ in my hometown in the past twenty years.

A. took place  B. have taken place C. were taken place       D. have been taken place

________ my hometown was a poor and backward area, but great changes ________.

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A．In the past, took place in the past years

B．In the past few years, have taken place in the past

C．In the past twenty years, took place in the past

D．In the past, have taken place in the past twenty years