用括号内所给单词的适当形式填空（5分）
小题1:My father is              (please) with my school work this year.
小题2:         (leaf) turn yellow in autumn because of the cool weather.
小题3:It is my grandma’s              (ninety) birthday.
小题4:This problem is not difficult. I can do it by myself            (easy)
小题5:Most boys enjoy         ( watch) NBA games.