要点包括：
1）锻炼的重要性；
2）锻炼有利学习；
3）提出锻炼建议。
注意：1）词数100左右；
2）可适当增加细节，以使行文连贯。
3）信的开头和结尾已为你写好。
Dear Lin Tao,
Sorry to hear that you have been sick for days and hope you are better now.
Sincerely yours,
Li Hua
Sorry to hear that you have been sick for days and hope you are better now. You have studied so hard that you have had no time to do any exercise, which does harm to your physical and mental health. It would be of great benefit to your he
