【简答题】When a sound is made just using air, it is called ‘_____________’; when a sound is made using one’s voice or vibration in the voice box, it is called ‘________’.
【单选题】For the proper control of the air temperature in an air conditioning system using chilled water circulation, which of the listed conditions should remain constant regardless of load changes? .
【简答题】A) When the warmer air meets with the cooler air. B) When the wind moves faster than 30 meters a second. C) When the seawater evaporates into the air. D) When the air gets wanner and warmer.