题目内容：

The Second World War had begun, and John w1. to join the army, but he was only 16 years old, and boys were allowed to join only if they were  o_2. eighteen. So when the army  d3._ checked him, he said that he was eighteen. But John's brother had joined the army a few days before, and the same doctor had checked him too. This doctor remember the older boy's family  n4., so when he saw John's papers, he was surprised. "How old are you?" he said." E5., sir," said John."But your brother was eighteen, too," said the doctor. "Are you twins?" "Oh, no, sir," said John, and his  f6. went red. "My brother is five months older than I am."