单项选择题 Every ship shall carry personnel qualified for（）to the satisfaction of the Administration.

单项选择题 All ships which, in accordance with the present Convention, are required to carry radio installations shall carry（）.

单项选择题 Digital Selective Calling means a technique using（）which which enables a radio station to establish contact with, and transfer information to another station or group of stations and complying with the relevant recommendations of the CCIR.