helical bevel gear
螺旋伞齿轮，斜齿伞齿轮

• dew point
• dextrorotation
• dextrorotatory
• diac
• diad
• diad axis
• diagnosis
• Diagnostic condensing lens
• Diagnostic Hruby fundus lens
• diagnostic program
• diagnostics
• diagonal
• diagonal angle of view
• diagonal choerent-state
• diagonal equation
• diagonal eyepiece
• diagonalization of intensity matrix
• diagonalization of matrix
• diagonal line
• diagonal plane
• diagonal position
• diagonal scale
• diagram
• diagrammatic representation
• diagrammatic view