What is in the middle of the classroom.

What is in the middle of the classroom. Millie is standing (exactly) in the middle of the classroom Millie is standing___(exactly)in the middle of the classroom what is in the middle of china? what is in middle of the world? What is in the middle of "Pairs" What is in the middle of the USA?(脑筋急转弯) What is standing in the middle of the wor 脑筋急转弯:what is in the middle of paris? 英语脑筋急转弯what is in the middle of water 3: what letter is in the middle of :paris"? what is the number in the middle