1. the word since is used to show a point of start.Use the word 'for' to show how long the action during.
The student sometimes mix the use of the word since and for.
2.This sentence is a question, do not forget the auxiliary 'do'. It is a rule in English to use the auxiliary. You have exceptions with questions beginning with word like 'wh....'.
3.Present perfect tense is for one action, is to show a during of the action in the past, I prefer the present perfect tense in this case.
Hope it's help you, try to resolve yourself your homework.
Have a nice day.
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