题目选项分析

Restorers say that if they are allowed to remove and replace the discolored layer of varnish on the Mona Lisa, the colors Leonardo da Vinci painted nearly five hundred years ago will once again shine through.

Restorers say that when it is allowed to remove and replace the discolored layer of varnish on the Mona Lisa, the colors Leonardo da Vinci painted nearly five hundred years ago will once again shine through.