今天讀到兩個例句：
(1)He was visiting an art museum about this time last week.
(2)He was working at McDonald's at that time.
想請問：
1. about 可以用at 或in 替換嗎？
2. 1、2句如果交換 意思相同還是會改變？
3. 除了 about/in/at this(that) time
還有其他類似的用法嗎？
先謝謝各位前輩了～～～^^

這邊 about 應該是大約的意思