سلام . ممنون میشم جمله های زیر رو ترجمه کنید.
Overpainting is one of the many problems facing art museum directors who are responsible for buying and evaluating works of art, who also have to be on guard for the false use of famous artists' names, false copies, or even fragments of paintings sold as whole works of art
Overpainting, the most common problem, results from the fact that quite often older works of art have been extensively changed
In addition to these two forms of deception, copies of famous paintings are sometimes sold as original works of art because some of the old masters painted a popular scene several times if it sold well or their students would copy their better works to practice style and technique