阅读下面这段话，用英语回答问题
I am Ken. Three years ago, I saw a beautiful stamp on an envelope. The letter was from my father's friend. I loved the stamp very much. My father let me keep it and that was the first stamp I had. Now I have about two hundred stamps. I always go to the post office to buy stamps at the weekend. Sometimes I use my pocket money to buy some stamps, but I can't buy the most beautiful ones. They are very dear. Now I have 10 pounds. It is just enough to buy a new stamp with a panda. So I get ready to go to the post office near my house.
（1）What did Ken see on the envelope?
（2）When did Ken have his first stamp?
（3）How many stamps does he have now?
（4）What does Ken do at the weekend?
（5）Why can't he buy the most beautiful stamps?