听下面一段材料,回答第1-3题。 1. What's the man asked to do for the exchange? A. Fill in a memo (备忘录) and show his passport. B. Sign a register and show his memo. C. Fill in a memo and show his ID card. 2. How much RMB can one get for one dollar according to the dialogue? A. 6.82 yuan. B. 6.62 yuan. C. 6.88 yuan. 3. How long is the valid period of the memo? A. One year. B. Six months. C. Three months.