用方框中所给单词的适当形式填空。

     Halloween is an old festival. Americans celebrate it every  . It comes on October 31st, the  before All-Saint's Day. It's a holiday for children. Every  , when the vegetables are ripe,  pick large pumpkins. Then they cut faces in the pumpkins and  lights inside. It looks like there is a person looking out of the pumpkin! The children  put on strange masks and clothes. Some children make their face  like monsters. Then they carry boxes to  money for "UNICEF" from door to door. They raise money to help  children all over the world. Of course, every time they help UNICEF, they usually  a treat for themselves, too.