未分类题You have just come back from a student exchange program in the U.S. Write a letter to your host family, the Smiths, in New York to express your gratitude for their hospitality, describe the help they gave you, offer to repay their help and invite them to visit you. You should write about 100 words on ANSWER SHEET 2. Do not sign your own name at the end of the letter. Use 'Li Ming' instead. Do not write the address.