Student or Learner
What is the difference between these 2 sentences.
1 I have seen him doing this.
2 I have seen him do this.
Are both sentences correct, if yes why if not why?
It's the normal difference between the progressive and non-progressive forms in such structures. If you see someone doing something, you see them in the process. You do not necessarily see them doing the whole action. If you see someone do something, you see the whole action. Compare:
I have seen John running a marathon.
I have seen John run 100 metres.