zone of opacity
(1) 不透明带，不透明区
(2)暗带，暗区

• mesh-dielectric mirror
• mesh electrode
• mesh of grid
• mesh spacing
• mesh storage tube
• symmetrical wave
• symmetrical wide-angle objective
• symmetroid
• symmetry
• sync
• synchro
• synchrocyclotron
• synchromesh
• synchromesh type transmission
• synchronism
• synchronization
• synchronization error
• synchronized shutter
• synchronizer
• synchronizing frequency
• synchronizing mode-licked
• synchronous
• synchronously demodulation
• synchronous pulsed holography
• synchronous tunable picosecond laser