Read the letter and underline the words/phrases in bold which are

Read the letter and underline the words/phrases in bold which are more polite and respectful.
Dear Mr. and Mrs. Smith.
1) I am writing to you to 2) thank you both very much for having let me stay with you. It was a great experience which I will always remember.
3) I really appreciate your efforts! Both of you мейд me feel like I was part of the family. My room was very comfortable and the home-cooked meals were delicious. I never thought I would have such a pleasant and memorable stay.
4) Also, living at your house over the summer months helped me a great deal with my language course. It gave me a chance to practice my English outside of the classroom. 5) It is for this reason that I have improved so much in such a short period of time.
6) Thank you once again for all your kindness. 7) My parents also send their regards and would like you to know that you 8)are welcome guests whenever you visit our country. I would love to hear from you whenever you have time to write.
9) Best wishes.
Ludmila