仿照例句用所给的词汇造句。
例：I, do my homework, last night
I was doing my homework last night.
A. they, have a dress rehearsal, yesterday evening
B. my grandma, visit my family, half an hour ago
C. I, travel in the south, at this time last year
D. they, build a power station, at that time
A. They were having a dress rehearsal yesterday evening.
B. My grandma was visiting my family half an hour ago.
C. I was traveling in the south at this time last year.
D. They were building a power station at that time.