单项选择题
On notification by Admiralty Notice to Mariners that a new edition of one of the books，or a new supplement to one，has been published，it should be obtained（）.
A.as soon as possible B.prior to its publication C.in advance of any possible accident D.by means of other than airmails
单项选择题 Navigational warnings and weather bulletins for shipping（）from Singapore Radio.
单项选择题 （）is the system for the broadcast and automatic reception of maritime safety information by means of narrow-band direct-printing telegraphy.
单项选择题 The fog most commonly encountered at sea is called（）.
