求大神指教.It's. a picture of a classroom为什么用of

求大神指教.It's. a picture of a classroom为什么用of 阅读理解Here is a picture.It's a picture of my classroom.In the 为什么“教室里的画"要说a picture of a classroom,而不能说a classroom's pictu Look !this is ().A a classroom 's picture.B a picture of a c It's a picture of — this is a picture of a classroom there is a picture of a classroom it`s a picture of jim`s family对picture of jim`s family提问 It\'s a picture of a sheep.画线部分提问? a picture of sb; one's picture 名词和冠词的使用为什么是a picture of a classroom?而不是the picture of the c Picture/it's/the/bridge/of/a连词成句