The problem is most people don’t know the safe way to surf the Web.問(wèn)題是大多數(shù)人不知道安全的上網(wǎng)方式。With such models, scientists have found out some key principles operating in food webs.通過(guò)這些模型，科學(xué)家們發(fā)現(xiàn)了食物網(wǎng)中的一些關(guān)鍵運(yùn)行原理。