阅读理解。 Mrs White has a son. His name is Sam White. The young man begins to work in a post office in a city this autumn. He asks his mother to visit (参观) the city. The old woman is happy and catches a train. Soon she gets to the city, but she doesn't know where the post office is She begins to look for it, but she can't find it. At a  bus stop she asks an old man, ' Excuse me, sir. How can I get to the post office?' ' We have about forty post offices in the city, '  says the old man. 'Which one do you want?' The old woman gives Sam's letter to him and the old man says, 'Walk along this street and take the fourth turning on the left. His post office is just there. ' Mrs White thanks the old man and soon finds her son. They're very happy. A week later (之后) the woman goes to the zoo. She sees all kinds of animals. But after that she can't find the way to the post office again. At the same bus stop she meets the same old man and she as the same question again. 'Oh dear!' the old man calls out. ' Are you still (仍然)looking for your son?' 1.___________,so she is happy. A. Sam White works in a post office B. Sam White works in a city C. Mrs White can visit the city D. Mrs White can live in the city 2.Mrs White goes to the city ___________. A. by train B. by bus C. by plane D. on foot 3.The old woman goes to the city for the first time, so___________. A. she wants to catch a bus B. she can't find the post office C. she likes to ask some questions D. she likes to go for a walk 4.___________,so she asks the old man again. A. Mrs White wants to go to the zoo B. Mrs White wants to thank the old man C. Mrs White is going to the park D. Mrs White forgets her son's post office 5.The old man thinks___________. A. Mrs White doesn't know the city B. Mrs White doesn't find her son C. Mrs White cannot take a bus D. Mrs White is too old