reversible spirit level
回转水准仪

• aliasing error
• alias-type transformation
• alibi-type transformation
• sulphide
• sulphide phosphor
• sulphur
• sulphur hexafluoride
• sulphuric-acid
• sulphuric-acid battery
• sulphurizing
• sulphur laser
• sulphur sensitization
• sum
• sum frequency
• sum frequency generation
• sumlamp
• summary counter
• summation
• summation actinometer
• summation law
• summer
• summit
• sump
• sunalux glass
• sun and planet gear