Dear Professor Smith, Would it be possible for you to give one of your lectures on America before the Spring Symposium (专题讨论会) to be held at our university on March 2nd, 1990 We have heard so much about your excellent work in America research that we are eager to have you accept our invitation. If you can accept our invitation, will you let us know before February 20 what your terms are and what facilities we should prepare for showing