1. 根据句意, 用所给单词的适当形式填空。

important   speak  nature  easy   three

1. （1） Do you know why Chinese has the largest number of English ?

3. （2） She has a ability to understand the motive(动机) of others.

5. （3） He says he never gives up though it's difficult.
   

7. （4） As we all know, China is the largest country in the world.

9. （5） He doesn't know the of washing hands before a meal.