Hi, Lucy,
I feel so sorry when I heard you were sick so badly and cannot go to school for about one month. I can understand your worries for your absence and here are some suggestions for you to be well prepared when you're off school. First, review what you've learned in school. Reviewing is a good way for you to make what you've learned more clearly and integrate. Second, learn something new by yourself daily. Even if you can understand little about the new stuff, some of them will still be absorbed by you and when you come back to school afterwards, you will learn those new knowledges quickly. Last and not the least, take good care of yourself, I really wish you will get well soon.
Yours sincerely
Hua Li