The past 30 years the great changes that have taken place in my hometown.A. sawB. was seen

问题补充：

The past 30 years the great changes that have taken place in my hometown.

A. saw

B. was seen

C. have seen

D. see

答案：

A. saw

B. was seen

(答案→)C. have seen

D. see

解析：表示过去的某一动作或行为一直持续到现在，故用现在完成时。