单项选择题
A.points of equal variation B.points of zero variation C.the magnetic latitude D.magnetic dip
Lines on a chart which connect points of equal magnetic...
单项选择题Lines on a chart which connect points of equal magnetic variation are called （）.
A.magnetic latitudes B.magnetic declinations C.dip D.isogonic lines
Many of the soundings shown on the chart are derived fr...
单项选择题Many of the soundings shown on the chart are derived from （）.Undue reliance should not be placed upon them．
A.complete and often very poor surveys B.correct and often very good surveys C.inadequate and often very old surveys D.adequate and present surveys
On this chart only the principle （） to navigation are s...
单项选择题On this chart only the principle （） to navigation are shown．
A.equipment's B.tools C.apparatus D.aids
