单项选择题

AREAS WHICH CANNOT BE SCANNED BY THE RADAR OF THE VESSEL BECAUSE THEY ARE SHIELDED BY PARTS OF ITS SUPERSTRUCTURE，MASTS，ETC means（）.

A.Blind sectors
B.Sheltered area
C.Unseen area
D.Unscanable area

点击查看答案&解析

上一题目录下一题

相关考题

单项选择题

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

单项选择题

An electronic depth finder operates on the principle that（）.

A.radio signals reflect from a solid surface
B.sound waves travel at a constant speed through water
C.radar signals travel at a constant speed through water
D.pressure increases with depth

单项选择题

An ECDIS is required to display which information?（）

A.Water temperature
B.Climatology data
C.Speed of advance
D.Depth contours