giúp em với ạ, em cảm ơn

TL:

21. The parcel which I was still at work then, arrived in the post at 11 a.m 

-> which thay cho the pracel 

22. Last week we visited the school which we went to together when we were in Atlanta 

-> which thay cho the school 

23. The hotel where we spent our honeymoon has been demolished 

-> where thay cho the hotel 

24. I still remember the day when my mother took me to school

-> when thay cho the day 

25. One reason why the panel could not decide who was the best person for the job was that the interview times were too short 

-> danh từ chỉ lý do why thay cho one reason