18．A young man was called up for army service，so he had to go to be medically examined．The doctor was sitting at a desk when he went in．He said to the young man，"Take your coat and shirt off，loosen your belt and sit on that chair．" After the young man heard this，he took off his coat and shirt quickly and loosened his belt and then sat down．The doctor looked at him for a moment without getting up from his chair and then said，"OK．Put on your clothes again．" The young man felt very puzzled and said，"But you haven't examined me at all!" "It is unnecessary，"the doctor said gently．"When I told you take off your coat and shirt，you heard me all right，so you aren't deaf．You saw the chair I pointed to，so your eyesight's good enough for the army．You managed to take your clothes off and to sit on the chair，so your body must be healthy，and you understood what I told you to do and did it without a mistake，so you must possess enough intelligence（智力） for the army．"
根据短文内容，回答下列问题． 96．What was the young man being medically examined for？For army service 97．How did the doctor know that the young man was not deaf？The young man had heard him all right． 98．How did the doctor know that the young man could see all right？The young man had seen the chair the doctorhad pointed to． 99．How did the doctor know that the young man's body was all right，too？The young man had managed to make his clothes off and to sit on the chair． 100．How did the doctor know that the young man was intelligent enough for the army？The young man had understood what the doctor had told him to do and had done it without a mistake．
