VE型不育－保持系
VE type male sterile-maitainble line
σ-闭包保持闭加细
clousure-preserving closed refinements
σ内部保持开膨胀
interior preserving of open expansions
安全车距保持系统
Safety distance keeping system
安全壳负压保持系统
containment subatmospheric pressure (maintenance) system
保持原状
background of feeling
background of globalization
保持边缘
keep the edge information
edge-preserving