Good subject  Khosro:

  Choosing a  "best" answer  is  nice for someone who answers, but not    completely necessary.

It will make somebody feel good; but if you do not choose a best,   people should not take offense at it.

  It is okay to just study all of the answers and then just  use what you learn.

   Sometimes  there are problems with answers.  For example,  someone may not understand  the question   but others will.  I think that students can feel sharply criticized  when others demand detail.

Sometimes,  one can use a little imagination and intuitively know that the student refers to.

   I do not ask questions generally but I do vote when I see others give good answers.

  Khosro:

  Sometimes I do feel bad if I do not get a  "best answer".  I rather like it.

It is a small reward, sometimes, for    detailed or extended explanation.

Sometimes I feel disappointed if I was entirely convinced of having a better answer.

   At the same time,  sometimes another person   deserves a "best answer"  and I am always eager to  give a  "thumbs up"  vote to someone else.  I have respect  for a great many of the members here.

   You should be aware that at times, there is a kind of "in-fighting" and competition between forum members.  The unfortunate side of that,  is that some members "block" others, which means that I am not allowed to respond to what they write; but it also means that  I cannot offer a "thumbs up"  vote for their answer  either.  It is rather a nice thing, you know,  when you or I or another   gets   3 or more "thumbs up" votes from other people.  Everybody likes that.

   I propose however, if  we are concerned about offending someone when there are several good answers together, the best course of action may be to just not choose a  "best answer".  That way, at least, the question stays open and still more people can answer it.  I will not be troubled if someone just does not choose.

   The good part about the subjects you post and the way that you post them,  is that they represent some of the more informative messages put in the Italki forum.  The one who can actually engage in dialogue with others,  is not only writing like a lady or gentleman,  they are displaying the faculty of high intelligence.

.

When only one person answers my questions,I choose her or him. But it is hard to choose somebody from many answers.

I do not want to offend someone:))

Khosro, I have never once chosen a best answer. I figure most of the time I'm not capable of even really knowing which one was best since I didn't know the answer to the question in the first place... that's why I asked it. 

Khosro

It is good of you to  want to nominate a "best answer" but I think most people who offer answers are not looking for any recognition - a polite thank you is more than adequate. That said, I am constantly amazed at the contributions of some of the people offering answers to questions about the use of English. Their expertise in English grammar and useage is outstanding and their explanations are clear and precise. Learners of English are getting high quality advice.