同为书为什么book就是a,english book就是an

同为书为什么book就是a,english book就是an 是an English book还是a English book 是an English book还是a English book? an english book复数形式 is ,an,book,english,this --It's a book.__ English book.A.A B.An C.The ( )useful book a/an That is an English book.给为复数形式 There is a book on the desk,and ____is an English book A.tha Write a review of an English book you read A; Who _____ an English book?B; I do . 用a/an填空 1 Is it( )Chinese book or ( )English book?2 This is