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单选题
74. 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
答案解析
正确答案：C
解析：
解析: 海图上很多水深信息是来源于不充分和非常老的数据,因而不应该完全相信
