Present Or Past Reporting Verb Version Dilemma In Reported S

[muratguler]

Hi All

I can't figure out where-when I should use these versions. Grammar book says, if the reporting verb is present simple, use "say-tell" and don't change the tense. For example....

direct speech: “I like ice cream”
reported speech: She says she likes ice cream

If the reporting verb is past, use backshift....

direct speech: “I like ice cream”
reported speech: She said she liked ice cream

The thing I cant understand is, when we report an expression that has already said, it is always a part of "past" and it seems to me that I should always use past reporting verb version. As you know, no tense change option is also available in past reporting verb version when the reported situation is still true. For example....

direct speech: “I am a student (2 years ago)
reported speech: She said she is a student. (now she is still student)

So why do we have present reporting verb version???

Please explain when we should prefer present reporting version and when we should prefer the past reporting verb version.

Thanks