1) Yesterday Mike found the book which he had lost in summer.
2) He had learnt English before he went to the USA.
3) When Mary rang me up, I was still reading the book which my friend had given me.
4) By the 1st of September all the children had returned from the country.
5) She wasn't discussing this problem with her director at this time yesterday. They discussed it last week.
6) When David entered the kitchen, he saw that the cat was drinking milk.
7) Jane told me yesterday that you had bought the nice shoes.
8) What were you doing at 8 o’clock yesterday? — I was repairing my car.
9) We didn't bring a lot of berries from the wood.
10) What was Kevin doing when you rang him up yesterday? — He was typing a letter.
глагол to be может быть глаголом-связкой в именном сказуемом (в значении "есть").-I am a doctor.Я врач. (Я есть врач.)
Чтобы задать вопрос нужно поставить глагол to be перед подлежащим:Am I happy?
Для образования отрицательной формы достаточно поставить отрицательную частицу not после глагола to be:I am not happy.