I have seen him go..

[thehammer]

Which ones are correct and what's the difference?

1- I have seen that he goes to scool on foot.
1a- I have seen him go to scool on foot.

2- I see him go to office every day.
2a- I see that he goes to office every day.

3- I saw him go fishing.
3a- I saw that he used to go fishing.
3b- I used to see him go fishing.

Could you please tell me when I should use "I saw/have seen that he/she/you....."
And when I should use "I saw/have seen him/her/you...."?

 

[Barque]

1 - You're talking about a regular occurrence that you've seen.
1a - You're talking about a specific event.
2 - You're talking about something you see every day.
2a - You're making an observation about what he regularly does.
3 - You saw a specific event.
3a - You're talking about something you saw him doing regularly.
3b - You're talking of something you'd see earlier but that you don't see now.

scool

Sounds like a cool school.

 

[Tarheel]

@thehammer
**I have seen that he goes to school on foot.**

That requires interpretation. Perhaps "I have watched as he walked to school" is what is meant.

______________________________________
If I was going to use that system I would give each number its own letter. (Those without them will feel resentful. )

 

[Barque]

I think he means "I've noticed that he walks to school (and doesn't take a bus or ride his bike)".

 

[Tarheel]

@thehammer For the first sentence, I think @Barque 's interpretation is better than mine. As for the second sentence, I think it means the same thing.

 

[Tarheel]

@thehammer Sentences 2a and 2b mean the same thing, which is either "I have noticed that he goes to the office every day" or "I watch as he goes to the office every day".

If I would say "I'm going fishing" that would mean that I am heading out to the place where the fishing will take place. However, all of your sentences seem to intend something else.