【单选题】Please confirm your attendance ________ by July 20, 2009.
【单选题】If you find our concesion ___, please confirm your acceptance by fax.
【单选题】If you find our concession ____, please confirm your acceptance by fax.
【单选题】Please confirm your attendance ________ by July 20, 2009.
【单选题】Please confirm your attendance ________ by July 20, 2018.
【单选题】Please confirm your attendance ________ by July 20, 2019.