Simplify the following text for a Grade 4 native English-speaking person.
Original: In singles , Petrova has reached a career high ranking of World No. 3 in May 2006 and has reached the semi-finals of the French Open in 2003 and 2005 .
Simplified: In singles , Petrova has a career high ranking of World No. 3 in May 2006 . She has reached the semi-finals of the French Open in 2003 and 2005 .