charter function造句

The carrier uses a fleet of coach-style buses to provide charter functions and a variety of services.
The charter functions as a contract in which the prospective school spells out how it plans to operate as well as what it vows to accomplish; the sponsoring agency monitors the school, and chooses whether to renew the charter at the end of a specified period, typically five years.
It's difficult to find charter function in a sentence. 用charter function造句挺难的