(四）、試述南北朝樂府民歌風格之不同？（二十分）

2. Which of the following is a continuous quantitative variable? Please write down your answers. A. the color of a student's eyesB. the temperature of the water C. the number of employees of an insurance company D. the amount of milk produced by a cow in one 24-hour period E. the number of gallons of milk sold at the local grocery store yesterday.