- 1.   
[构成疑问句]  -  
• Do you smoke? 你抽烟吗? - 2.   
[构成否定句]  -  
• He doesn't bow before difficulties. 他不向困难低头。 -  
• Don't be silly. 别傻了! - 3.   
[用以加强语气]  -  
• Do be careful! 千万小心。 -  
• I did go, but she wasn't in. 我的确去了,但她不在家。 - 4.   
[用于倒装句]  -  
• Well do I remember it. 那我可记得清清楚楚。 -  
• Little does he know. 他(对…)知道得很少。 - 5.   
[用于省略句或用以替代动词或词组]  -  
• You know her better than I do. 你比我更了解她。 -  
• I wanted to go and I did so. 我想去,于是就去了。