你所说的没有主语（包括祈使句）实际上都是省略了主语(甚至谓语,宾语）.前提是在说话人双方都能理解的语境条件发生的.
除祈使句外,还有以下形式
1
-who's that?
-(it's) Me.
2
-Will you come tonight
-(I will come)Abosolutely!
3
-How are you?
-(I'm) Fine,(I) thank you.