Are you a student? englishmed.com/nurses * Google Inc impressed investors, but people'schanging behavior on mobile phones and even on desktopsthreatens the company's main business. The results revealed thecompany's deep challenges: as its desktop search and advertisingbusinesses mature, along with overall business in the UnitedStates, its growth rate is slowing and the amount of money itmakes from each ad it sells is falling. ()