Great changes____ in our country during the past 20 years.

During the past five years,there ＿＿＿（be）great changes in our great changes ___in our hometown in the past ten years Our hometown has w——many great changes in the past 20 years There ------great changes in our country in the past few yea Great changes( )place in China in the past 20 years. In the past three years,we ( ) great progress in our study. In the past ten years there ___ great changes in our hometow there——great changes in our town in the past fifteen years.A Great（）have taken place in our city in the past twenty years great changes----in our city in the past three years 1took p for the past two years great changes（ ）in our town .（take）应该 In the last 30years , our country has e__ great changes e开头的