Mr . m answers : " although it is an important method to keep oral hygiene , oral microorganisms and some virus do not only exist on the surface of teeth but also between spaces of teeth and in the whole oral cavity where they collect and multiply M先生答：刷牙是保持口腔卫生的重要手段，但口腔微生物和一些病毒并不只是粘附在牙表面。牙缝及整个口腔都是微生物和病毒生存繁衍的温床。
