下图是小球平抛运动轨迹中的三点，测得A、B间和B、C间的水平距离分别为x1和x2

A. What do you think of Beijing?  B. I’ll bring them to school tomorrow. C. It was great.    D. Did you see any popular stars?

 
A: How was your vacation, LiLei?
B: 47 I went to Beijing with my parents.
A: Cool! Where did you go in Beijing?
B: We went to the Summer Palace, the Palace Museum and so on.
A: 48
B: It’s interesting. I really like the Palace Museum. It has many beautiful things from different dynasties.
A: 49
B: Yes, I did. I saw Jackie Chan on the Great Wall. And I got his autograph.
A: Wow, that’s great! Could you show me his autograph?
B: Yes, sure. 50