答案：Dear all,
I'd like to recommend Zhang Li as the chairperson of the Students' Union.
Zhang Li studies very hard and she has gone far beyond all her classmates in study. She is very modest and never shows off before others. She is also creative. She often comes up with good ideas. She is so helpful that she always helps the classmates with their schoolwork. Last week, I failed the Maths exam and felt very sad. She advised me to achieve a balance between schoolwork and rest and encouraged me not to give up easily.
I think Zhang Li has all the qualities to be the chairperson and she will be a good leader.
Yours sincerely,
Wang Hua