单项选择题 Director Gary Robertson’s latest film,《Frontiers》centers on the______of a young man who traveled to the American West in the 1850s, seeking fortune and fame.（）

单项选择题 ______the Radio Communications Directory, there are 16,376 licensed radio stations currently broadcasting.（）

单项选择题 The average______for a 2-bedroom apartment in Boulder, Colorado is $900 a month.（）