Mrs White has a son．His name is Sam white．The young man began to work in a post office(邮局) in a city this autumn．He asked his mother to visit the city．The old woman was happy and caught a train．Soon she got to the city, but she didn’t know where the post office was．She began to look for it，but she couldn’t find it．At a bus stop she asked an old man，“Excuse me，how can I get to the post office?”
“We have about forty post offices in our city,”said the old man．“Which one do you want?” Mrs White gave Sam’s letter to the old man and he said．“Walk along this street and take the fourth turning on the 1eft．His post office is just there．”
Mrs White thanked the old man and soon found her son．They were very happy．A week later she went to the zoo．She saw many kinds of animals．But after that she couldn’t find the way to the post office again．At the same bus stop she met the same old man and she asked the same question again．
“Oh dear!’’the old man called out．“Are you still looking for your Son?”
根据短文内容，回答下列问题。
Where did Sam White work?
How did Mrs White go to the city?
Did Mrs White know how to get to her son’s post office'?
How many post offices are there in this city'?
Did Mrs White know the way to the post office when she came out of the Zoo?