Exercise 3.  сделайте предложения отрицательными.
  the teacher was explaining the exercise to the pupils.
  amanda was travelling around africa at that time.
  we were having a music lesson at ten o’clock yesterday.
  i was doing the shopping yesterday.
  martin was visiting his aunt at this time yesterday.
  the girls were preparing for the concert.
they were flying to wales at 6 o’clock yesterday.
it was raining hard all day last tuesday.
  mike and jess were walking in the park last evening.
  he was choosing the books in the library then.

The teacher was not explaining the exercise to the pupils.

Amanda was not  travelling around Africa at that time.

We were not  having a Music lesson at ten o’clock yesterday.

I was  not doing the shopping yesterday.

Martin was not visiting his aunt at this time yesterday.

The girls were not preparing for the concert.

They were not flying to Wales at 6 o’clock yesterday.

It was not raining hard all day last Tuesday.

Mike and Jess were not  walking in the park last evening.

He was not choosing the books in the library then.

Объяснение:

Также можно использовать сокращенную форму: wasn't, weren't