Объясните почему в предложении
had flown почему past perfect ,а не past pefect continuous или past simple
one night a little swallow was flying over the city. his friends had flown away to egypt 6 weeks before ,but he had stayed behind. ​

Moscow [или другой город]
Russia
9th of March
Dear [имя],
Thank you for your letter. I want to tell you some interesting news. I have became a volunteer. My friends and I help old people after school. We get together and help them to clean their house, wash the dishes or to cook food. It isn’t very easy sometimes but I am very happy to make their lives simplify. Our volunteers’ organization have its own name and slogan. We wear special uniform - green T-shirts. I think it will be really great if you join our volunteer organization. Because it is so cool we you help people around us!
Sorry, I have to go to my volunteer friends now, I’ll write you later.
Write back soon
Best wishes,
Kate [твое имя]

1. My friend asked if I was busy with yesterday evening.

2. The librarian asked me where did I take this book.

3. His Grandmother asked him who does this boy remind him of.

4. A little boy said that his mother grows many flowers in her garden, but he doesn't know their names.

5. The girl said that she prefers pancakes with caviar, she doesn't like sour cream.

6. The teacher asked me what is the best time to visit me.

7. The reporter said that they didn't take the law.

8. The doctor said that nothing can influence me.

9. Her classmate said that she likes to show off very much.

10. The boy apologized and said that he didn't notice his friend.