安全经济效益
the economy benefit of safety
benefits of safety operation
safety economic benefit
safe economic benefit
安全经济效益评析
discussing safety economic benefit
安全效益
safe performance
benifit from safe operation
safety benefit
safety benefits
safety benifit
safety effect
safety profit
安装位置及效益
install location and benefit
办学效益
educational efficiency
benefit of education
benefit of running schools
school benefit
effiency of running school
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