单项选择题
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
To agree with larger scale chart，latitudes taken from t...
单项选择题To agree with larger scale chart，latitudes taken from this chart should be increased （） about 8 seconds．
A.with B.in C.by D.to
