阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。
Practice does not (necessary) make perfect. A study of violinists found that merely good players practised as much as, if not more than, better players, (leave) other factors such as quality of tuition, learning skills and perhaps natural talent to account the difference.
The work is the latest blow to the 10,000-hour rule, the idea promoted in Malcolm Gladwell's 2008 book, Outliers, which has been taken to mean enough practice will make an expert of anyone. In the book, Gladwell states that "ten thousand hours is the magic number of greatness".
"The idea has become really rooted in our culture, it's an oversimplification," said Brooke Macnamara, a psychologist at Case Western Reserve University in Cleveland, Ohio. "When it comes to human skill, a complex (combine) of environmental factors, genetic factors and (they) interactions (explain) the performance differences across people."
The seed for the 10,000-hour rule was a 1993 study of violinists and pianists found that (accumulate) practice time rose with musical prowess. On average, top-ranked violinists had clocked up 10,000 hours of practice by the age of 20, though many had actually put in fewer hours.