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单选题
An indirect radar echo is caused by a reflection of the main lobe of the radar beam off the observer’s vessel. Which of the following is NOT a characteristic of indirect echoes?（）.
A
Their bearing is almost constant，even when the true bearing of the contact changes appreciably
B
They always appear on a bearing of 90°from the true bearing of the contact
C
The indirect echoes usually appear in shadow sectors
D
When plotted，their movements are usually abnormal
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更多 “单选题An indirect radar echo is caused by a reflection of the main lobe of the radar beam off the observer’s vessel. Which of the following is NOT a characteristic of indirect echoes?（）.A Their bearing is almost constant，even when the true bearing of the contact changes appreciablyB They always appear on a bearing of 90°from the true bearing of the contactC The indirect echoes usually appear in shadow sectorsD When plotted，their movements are usually abnormal” 相关考题
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