She was working on the problem this time yesterday.

　　她昨天這時候正在解那道題。

　　What were you doing at this time yesterday?

　　昨天此時你們在干什么？

　　Can you tell me what they were doing this time yesterday?

　　你能告訴我他們昨天這時候在干什么嗎？

　　This time yesterday, we were having an English lesson.

　　昨地這個時候，人們正正鄙人英語課。

　　He can't have been in his office this time yesterday.

　　昨天這個時間他不可能在他的辦公室里。