Tom, Bill and Dave lost their backpacks(背包). They are at the Lost and Found desk The backpacks are the same, but the things in them are different Can you help them find the right backpack? Tom: I have a math book and a pencil case in my backpack. There are three pencils, a pen and an eraser in the pencil case. Bill: I have a Chinese dictionary, a math book and two notebooks in my backpack. Dave: There are two CDs, three picture books in my backpack. My English book is also in it. ( ) 58.The three boys lost their____.