單項選擇題A mean sun is used as the reference for solar time for three reasons. Which reason is NOT a cause for use of a mean sun?（）

A.The motion of the apparent sun is along the ecliptic
B.Measurement of time is along the celestial equator
C.The speed of the Earth's revolution is not constant
D.There are variations in the Earth's rotational speed


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1.單項選擇題A marine chemist issues gas free certificates and is certified by which organization? （）

A.Mine Safety Appliance Association
B.American Chemical Society
C.Marine Chemists Association
D.National Fire Protection Association

2.單項選擇題A major health hazard of the product tert-butylamine is that it （）.

A.can be absorbed through the skin
B.causes irreversible damage to eye tissue
C.is a very unstable product
D.All of the above

4.單項選擇題A low HDOP (Horizontal Dilution of Precision) number such as 2 indicates a （）.

A.poor fix
B.good fix
C.poor signal quality
D.good signal quality

5.單項選擇題A list signal of one white light indicates that the vessel is （）.

A.on an even keel
B.listing about 1° to the side the light is displayed on
C.listing over 5° With the light displayed on the high side
D.listing，and the chutes should be directed to the side where the light is displayed