单项选择题
Which is not a significant difference between manufacturing and service operations？（）
A.cost per unitB.uniformity of outputC.labor content of jobsD.customer contactE.measurement of productivity
单项选择题 In some European nations，the working people may face much higher taxes because（）.
单项选择题 China has cut its rate of population growth by（）since 1970.
单项选择题 Which of the following is not mentioned in the passage as a reason for birth rate drop？（）
