To hear/see/ watch... + O + bare-Inf.<br/><br/>To hear/see/ watch... + O + gerund<br/><br/>EX: I saw him do it yesterday. (witness the action from beginning to the end?)<br/><br/> I saw him doing it yesterday. (witness the action is happening?)<br/><br/>How to distinguish two above forms based on meaning. Are there some signals? Plz help me!