光谱方案
电气系统控制线路由()组成。 ["主回路","接触器","熔断器","继电器","控制回路"]
Which determines if “prefs” is a directory and exists on the file system?() [" Boolean exists=Directory.exists (“prefs”);"," Boolean exists=(new File(“prefs”)).isDir();"," Boolean exists=(new Directory(“prefs”)).exists();"," Boolean exists=(new File(“prefs”)).isDirectory();"," Boolean exists=true; Try{ Directory d = new Directory(“prefs”); } catch (FileNotFoundException e) { exists = false; }"]
课程编制的过程模式
燃料被加热到(),才能进行燃烧。 ["着火点","闪点","燃点"]
简述马斯洛需求层次理论的内容。