(1)水位

(2)水印
纸张上隐含在照明时可见的图文，通常用以指示文件或文件制作者的真确性。

• authorized capital
• authorized capital stock
• authorized stock
• authorized stock issue
• Authorized Version
• authorship
• au tiel forme
• autocracy
• auto da fe
• auto de fe
• autograph
• automatic continuance
• automatic insurance
• automatic revocation of trust
• automatic stay
• automatic suspension
• automatism
• automobile accident
• automobile association
• automobile club
• automobile collision insurance
• automobile comprehensive insurance
• Automobile Dealers' Day in Court Act
• automobile fire insurance
• automobile guest