用括号中所给词的正确形式填空。

1. —Where is the bird? 

   —It ________ (fly) away a moment ago.

2. He is worried about _________ (not pass) the English exam.

3. Amy would rather ___________ (wear) green than red. Red is a girl's color.

4. He told me that he would have some difficulty                 (chat) with American students.

5. It is generous of the people from the rich family_________ (donate) to UNICEF.

6. — Hi, Liu Tao. I didn't see you at the party.

    —Oh. I _______ (get) ready for the maths exam.