You want to invite Mr. Williams to give a lecture on “American literature” in your college. Suppose you are the assistant of the English Department， write a letter and say：
1) the purpose of the invitation，
2) the time of the lecture.
Your letter should be no less than 100 words. You don’t need to write the address. Don’t sign your own name at the end of the letter. Use Li Ming instead.
Dear Mr. Williams，
I am writing on behalf of the English Department to invite you to give a lecture in our college.
We know that you are an expert on American literature. As English majors， our students would like to know something about American literature. We would be very grateful if you could give a talk on “Contemporary American Literature” to students of the English Department on Saturday， June 4. If this subject does not suit you， any other similar topic would be welcomed as well.
We have already had several very interesting talks from some distinguished visitors from various countries and we look forward early to the opportunity to benefit from your experience and wisdom.