你可能感興趣的試題

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

單項(xiàng)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

A message by flashing light consists of the call，the identity，the text，and the （）.

你可能感興趣的試題

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 marine chemist issues gas free certificates and is certified by which organization? （）

A message by flashing light consists of the call，the identity，the text，and the （）.