题目

More than half of high school students surveyed reported at least one symptom (症状) of hearing loss connected with the use of portable music players, like iPods and other MP3 players. Does your child turn up the volume (音量) on the television or radio, even though everyone else can hear just fine? Does your child say “what？” or “huh？” repeatedly? It could be their ear－bud head－phones, which, like the ones typically used with iPods and other portable music players, project sound directly into the ear canal (耳孔)． Sound levels are measured in decibels. Generally, decib对生物的生存来说，不是它生长的基本条件的是（　　）A．空间B．温度C．营养D．时间