You went away with your English friend Alex and his family. Writte an email to Alex. In your email, you should:
+Thank him
+Say what you enjoyed most
+Invite Alex to do something
Dear Alex! Thank you very much for letting me accompany your family on the trip. That makes me have a great vacation. So, in return, I hope you and your family will come to the picnic with me. Best friend, Hoai Anh