1 . I’d like to represent a problem to the school on ________ of (代表) the student union. (根据汉语提示单词拼写)

2 . I’m writing on ______(代表) of my mother to express her thanks for your gift. (根据汉语提示单词拼写)

3 . O________ our school, I am writing to invite you to serve as a judge in the English Poetry Contest. （根据首字母填空）