leveling
(1)水准测量
(2)校平，调平
(3)矫正，矫直

• man-made satellite
• manometer
• man-portable laser
• mantissa
• manual control
• manual data input equipment
• manual gear shifting
• manual operation
• Manual ophthalmic surgical instrument
• Manual refractor
• manual turn knob
• many-element laser
• many line spectrum
• MAOS
• map
• maping infromation
• mapper
• mapping camera
• mapping equipment
• mapping function
• mapping IR-system
• marble
• marcroentgenogram
• margin
• marginal absorption