I take it that zheke01 is referring to right clicking on a file , folder , or other media and selecting from the context menu , "Scan with Avast!" . That's my take on the question .
zheke01, from my experience of such a scan method I will see some activity , such as a popup from Avast! , and then it will stop . If the "right clicked" context menu scan found anything you would be alerted , for sure . No response is a indication of a clean scanned object I believe .