Mr
/ˈmɪstə(r)/noun
1- a title used before a surname or full name to address or refer to a man without a higher or honorific or professional title用于姓或姓名前 先生：
Mr Robert Smith.
罗伯特·史密斯先生。
1.1
- used before the name of an office to address a man who holds it用在职务之前 先生：
yes, Mr President.
是, 总统先生。
1.2
- (in the UK) used before a surname to address or refer to a male surgeon（英国）［用于男性外科医生的姓前］ 先生。
1.3
- used in the armed forces to address a senior warrant officer, officer cadet, or junior naval officer［军队中用于称呼一级准尉、见习军官或低级海军军官］ 先生。
词源
late Middle English: originally an abbreviation of MASTER1 ; compare with MISTER.