Hi,
1)Does it mean before "i.e.", we can only memtion one thing? Yes.
2)My teacher tell us that if we use "for example", we can't not use incomplete sentence after it. It depends what you mean by an incomplete sentence.
(a) Doing project is good for us.For example, Tom learns how to communicate with other people thorough the project. ---correct Yes
(b)I learn something thorought the project for example, communicate with other people, become more independent---wrong
Why? Your example needs to be a noun, or something like a noun, eg a noun clause, or a gerund. So, you'd need to say
I learn something thorought the project for example, how to communicate with other people, how to become more independent
I learn something thorought the project for example, communication with other people, greater independence
3)"and so on" and "etc." can't follow "i.e." , "e.g." and "for example" <<<right? Generally speaking, right.
4)When can i use "and so on" this word (Can someone give me a example)? This phrase means '.... and in other similar ways', '..... and others of the same kind'.
You can improve your English by watching English movies, reading English newpapers, and so on.
A slightly different wording for this phrase is '.... and so forth'. To add emphasis, we sometimes say both, ie '...and so on and so forth'.
Best wishes, Clive