One day, I happened to meet an Englishman in the street and soon we began to talk. As I was talking about how I was studying English, the foreigner seemed to be very surprised, gently shaking his head and saying “You don’t say!”
I was confused, and I thought, “Perhaps this is not a right thing to talk about.” Then I said to him, “Well, shall we talk about the Great Wall? Have you ever visited it?”
“Certainly! Everyone back home will laugh at me if I leave here without seeing it. The Great Wall is wonderful! ” “Yes, it is one of the wonders in the world. And people of many countries have come to visit it.” As I went on telling him more about it, he stopped me again, “You don’t say!”
I couldn’t help asking, “Why couldn’t I talk about it?”
“Well, I didn’t stop you talking about it,” he answered, greatly surprised.
“Didn’t you say ‘You don’t say!’?” I asked again.
Hearing this, the foreigner laughed loudly. He began to explain, “’You don’t say!’ means ‘Really’. Perhaps you know little about English idioms(习惯用语).”
Wow! How foolish I was! Since then I have been careful with English idioms.
【小题1】What made the foreigner laugh loudly?

One day I happened to meet an Englishman in the street and soon we began to talk. As I  was talking about how I was studying English, the foreigner seemed to be very surprised, gently shaking his head and saying “You don’t say!” I was puzzled, and I thought , “Perhaps this is not a right thing to talk about.” So I said to him, “Well, shall we talk about the Great Wall? Have you ever been there?”
“Certainly! Everyone back home will laugh at me if I leave here without seeing it. The Great Wall is wonderful!” “Yes, it is one of the wonders in the world. And people of many countries have come to visit it.” As I went on telling him more about it, he stopped me again, “You don’t say!”
I couldn’t help asking, “Why do you ask me not to talk about it? ”
“Well, I didn’t ask you to do so,” he answered, greatly surprised.
“Did you say ‘You don’t say!’?” I asked again.
Hearing this, the foreigner laughed loudly. He began to explain, “‘You don’t say!’ means ‘Really’. Perhaps you know little about English idioms(惯用语).”
Wow! How foolish I was! Since then I have been careful with English idioms.
【小题1】The writer was puzzled because                  .