It may be found that，in certain circumstances，radar beacon emissions can cause（）with the normal radar display，particularly at close range.

单项选择题Radar reflectors are required for（）.

A.all fishing vessels over 39 feet in length
B.sail-propelled fishing vessels
C.all fishing vessels of less than 200 GT
D.wooden hull fishing vessels with a poor radar echo

单项选择题Radar makes it possible and much safer for us to sail（）.

A.in dense fog
B.in boisterous weather
C.in the open sea
D.in rivers

单项选择题Radar beacons are transmitters designed to produce a（）on the screens of ship’s radar sets.

A.incorrect image
B.distinctive image
C.pictorial image
D.pictographic image

单项选择题Proper use shall be made（）radar equipment.

A.with
B.to
C.for
D.of

单项选择题No assumptions（）on the basis of scanty information，especially scanty radar information.

A.should not be made
B.are not to be taken
C.should be taken
D.shall be made