(Английский) Поставьте глаголы в скобках в соответствующее время, указать какое время и почему?

He was preparing for the lessons all last night. What were you doing when I called you?

I didn't sleep at nine o'clock yesterday.

What is he doing? - He reads a scientific journal.

＿ Have you read any stories by Jack London?

What are you doing here? - I wrote a letter to my friend. We have already learned a lot of English words.