The steady hum of school heating systems and air-conditioners can mean lower test scores f

or many young students, found a new study. The finding adds to growing evidence that classroom noises【C1】______ with learning. Plenty of studies have demonstrated the distracting【C2】______of noise in the classroom. In louder rooms, kids have more trouble hearing the teacher and become easily distracted,【C3】______when they are reading to themselves. Schools【C4】______ airports also report lower test scores than schools that are not affected by airplane noise. In one study, German students started scoring better on reading and vocabulary tests after a nearby airport【C5】______. Researchers were also interested in less【C6】______ sounds like the general buzz of basic mechanical systems. It was【C7】______that kids who spent all day in classrooms with such noises【C8】______ to score lower on standard reading comprehension tests. But math scores didnt【C9】______ with noise levels, possibly because teachers use more【C10】______ when theyre teaching math than when theyre teaching words. 【C11】______, lots of background noise sets kids up for problems. Studies have shown that kids make more noise in louder rooms.【C12】______by the scraping of chairs, the hum of the heating system,【C13】______the voices of other kids competing to be heard, some students【C14】______have a particularly hard time hearing【C15】______ the teacher is saying. And its not that theyre lazy or using noise as an【C16】______. Young brains have a much harder time【C17】______a signal from the background than mature, adult brains do. Along with【C18】______work, the new findings suggest the【C19】______ for enforcement of ANSIs standards. Despite an endless list of budgetary【C20】______, schools might have to put quiet at the top of their to-do lists.

【C1】

A．vibrate

B．interfere

C．increase

D．vanish