用所给单词的适当形式填空  

1. Can you give me your _________(explain) for your absence?  

2. During the Spring holidays there are many _______ (culture)activities.  

3. In America, we often greet people by ________(shake) hands or hugging. 

4. I'll call you as soon as I ________(get to) New York.  

5. Could you tell me some special customs that ________(not find) in Chinese culture?

有红、黄、蓝三种颜色的小珠子各4颗混放在口袋里，为了保证一次能取到2颗颜色相同的珠子，一次至少要取______颗．

如果要保证一次取到两种不同颜色的珠子各2颗，那么一定至少要取出______

颗．