What is the most famous painting by the Italian artist Leonardo da Vinci (列奥纳多·达·芬奇)? Of course, it is the Mona Lisa. Many art lovers are amazed by Mona Lisa’s mysterious (神秘的) smile. However, does Mona Lisa really smile? People have different opinions about this. Some think that she is smiling, while others believe she is grimacing (愁眉苦脸). Now, scientists may be able to help figure this out.