1 said had been
2 remembered had left
3 wrote had had
4 came left went
5 received had not heard
6 read has gone
1) my granny said that she had never been to London before
2) He remembered that he had left his hat at the theatre
3) She wrote that she had had a good sighteeing tour around London
4)The travellers came to the hotel, left their bags there and went for a walk in the town
5)Yesterday I received a letter from my friend,from whom I had not heard for a long time
6) We read in yesterday's newspaper that a group of doctors from Ukraine went to London to take part in a conference