get a good grades这里有了冠词s为什么还要加s

get a good grades这里有了冠词s为什么还要加s to get better grades,grade为什么要加s It s my dream ( get)good grades It's necessary ____ us____ good grades.A for get B to gettin It's hard to get good grades.同义句 That sounds good.这里的sound为什么要加s? my new year's resolution is to get good grades.这句中 is to get the best grades of tea 的grades 为什么要加S It's good exercise.为什么good前不用加a? it's __for you to get good grades.(hope) 根据适当形式填空 I will do 可以这样说不:although get good grades is important,children's happ 英语 这里为什么加S?