精选优质文档-倾情为你奉上The human nose is an underrated tool.Humans are often thought to be insensitive smellers compared with animals,1 this is largely because,2 animals,we stand upright.This means that our noses are 3 to perceiving those smells which float through the air,4 the majority of smells which stick to surfaces.In fact5,we are extremely sensitive to smells,6 we do not generally realize it.Our noses are capable of 7 human smells even when these are 8 to far below one part in one million.S
