Questão 26

Studies have shown that assiduous instrument training from an early age can help the brain to process sounds better, making it easier to stay focused when absorbing other subjects, from literature to tensor calculus. The musically adept are better able to concentrate on a biology lesson despite the racket in the classroom or, a few years later, to finish a call with a client when a colleague in the next cubicle starts screaming at an underling. They can attend to several things at once in the mental scratch pad called working memory, an essential skill in this era of multitasking […]Sadly, fewer schools are giving students an opportunity to learn an instrument.

(adapted from http://www.scientificamerican.com/article.cfm?id=hearing-themusic- honing)

In “Studies have shown”, the correct forms of the underlined verb are: