If you buy a book,you can both order one online and buy one

If you buy a book,you can both order one online and buy one If you can't afford to buy a new house,you can ________ one if you have a choice,______（buy）one large. what an interesting book? you can buy (it / one) in the book If you are poor and can't go to a good shool,can one book ch (5% off if you buy online) I will buy you a new one If you buy one,you can get another free of c___(缺词填空） You can buy the computer by yourself one day if you ___ mone If you buy a $5 sandwich,you'll get the second one at $2.50 can you tell me which one ----------(to buy/buying) John wants a car and he can't buy one.