用括號中所給詞的正確形式填空。
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.