答案:Dear Professor Smith,The fifth International Conference on Chemical Engineering will be held this autumn at Beijing University. We take great pleasure in inviting you to attend this meeting. Usually, there were about 500 scientists and experts from all over the world participating in the conference.If you have any papers to submit or topics on which you would like to give talks, please inform us as soon as possible in order to finalize the program soon.All your expenses, except air fare, will be born by us. Please confirm your participation at your earliest convenience.With best regards.Yours sincerely,Prof. Zhang Yuan