Linda has been suffering from migraine for a long time. Over the (passed/past) few years, she has sought advice from different doctors and even undergone some treatments. However, she made little improvement. The illness (persists/persevere/insist) without signs of abating. She feels so helpless that she is about to go to a guy, who claims to possess some special medicine for her. Knowing her intension, her brother (persists/perseveres/insists) that she demand all the adversary effects of the medicine. “I (presume/assume) that there are a lot of quacks out there and the guy you just mentioned is probably one of them,” he said. “I don’t know! But it’s true that I’d better be more (prudent/prudential) on this matter. Thank you for timely reminding me,” she replied.