All of the following are part of the fire triangle EXCEPT（）.

单项选择题All Loran-C transmitting stations are equipped with cesium frequency standards which permit （）.

A.every station in one chain to transmit at the same time
B.each station to transmit without reference to another station
C.on-line transmission of single-line transmitters at the same time
D.each station to only depend on the master for synchronization and signal ratio

单项选择题Air circulation is caused or affected by（）.

A.the rotation of the earth on its axis
B.convection currents caused by differences in radiant heating between equatorial and polar regions
C.mountain ranges
D.All of the above

单项选择题Aids to navigation marking the intracoastal waterway can be identified by（）.

A.the letters ICW after the aid's number or letter
B.yellow stripes，squares，or triangles marked on them
C.white retroreflective material
D.the light characteristic and color for lighted aids

单项选择题After you get underway，what is the first river gage you will pass? （）

A.Bayou Sara
B.Baton Rouge
C.Head of Passes
D.Red River Landing

单项选择题After you enter Thimble Shoal Channel，you will alter course to pass between Trestle “A” and “B”. Which channel should you use?（）

A.Thimble Shoal Main Channel or the South Auxiliary Channel
B.Any of the channels but keep to the right hand side
C.The South Auxiliary Channel
D.Thimble Shoal Main Channel