安全经济效益
the economy benefit of safety
safety economic benefit
safe economic benefit
benefits of safety operation
安全经济效益评析
discussing safety economic benefit
安全效益
safe performance
safety benefit
safety benefits
safety benifit
safety effect
safety profit
benifit from safe operation
安装位置及效益
install location and benefit
办学效益
benefit of education
benefit of running schools
effiency of running school
educational efficiency
school benefit
school-running benefit
保土效益
Soil conservation benefit
边际经济效益
marginal economic benefits
边际效益递减原理
based on Law of Diminishing Marginal Utility