单项选择题
Navigational charts are （） frequent changes，the important one of which are promulgated by Admiralty Notices to Mariners．
A.published with B.combined with C.in connection with D.subject to
单项选择题 My position has been obtained （） astronomical observation．
单项选择题 Magnetic information on a chart may be （）.
单项选择题 Entering from sea，a daymark on the port side of the channel would be indicated on a chart by a （）.
