根据写作要求，写出一篇作文。 You are Susan. Your company will hold an opening ceremony for a new factory. You are asked to write an invitation letter to David， an important client of your company. The following information should he included：the reasons to invite him； the time for the event；the place for the event；early reply expected. 

Dear David：
It would give us great pleasure to have your presence at the opening ceremony for a new factory. scheduled for 2017.11.20， at the factory.
Your presence would contribute greatly to the success of the ceremony. please let me know as soon as possible if you can come.
Your sincerely                                                                             lizixian