One possible version:
June 8, 20xx Dear Sir, I'm sorry to tell you that I can't go to school today, I've caught a cold because I swam in the school's swimming pool yesterday. This morning I had a headache. After taking my temperature, my mother found that I had a high fever, immediately she took me to see a doctor, who advised me to stay in bed for 2 days. Now I am writing to you to ask for 2 days' sick leave. With best wishes.
Your student,Tom
Dear Mr.,
I'm sorry to tell you that I caught a cold and I'm not feeling well now.I am adviced to stay in bed for two days and can't go to school then.But I think I'll get well soon and be back the day after tomorrow.
Yours sincerely,
One possible version:
June 8, 20xx Dear Sir, I'm sorry to tell you that I can't go to school today, I've caught a cold because I swam in the school's swimming pool yesterday. This morning I had a headache. After taking my temperature, my mother found that I had a high fever, immediately she took me to see a doctor, who advised me to stay in bed for 2 days. Now I am writing to you to ask for 2 days' sick leave. With best wishes.
Your student,
Tom
zhang:
today, i have a fever because of the cold, not class, leave one day, your approval!
leave: tintin
in june 11th -
张老师，我今天因为感冒发烧而请假一天，望批准!
Dear Mr/Ms ...,
I'm not feeling very well today. I've got a bad cold. My father took me to see a doctor this morning, and the doctor looked me over carefully and gave me some medicine. He also advised me to stay in bed for a day. So I can't go to school today. I hope I'll get weel soon and go to school tomorrow morning. Thanks.
Your student
Dear Mr.,
I'm sorry to tell you that I caught a cold and I'm not feeling well now.I am adviced to stay in bed for two days and can't go to school then.But I think I'll get well soon and be back the day after tomorrow.
Yours sincerely,
Dear Mr/Ms ：
Today I'm writing to you to ask for a five-day leave, for I've got cold last night with carlessness.This morning my mother took me to see the doctor,who told me to stay in bed for some days. So I am very sorry to be absent from school, especially your interesting lessons. I'll be sure to make up for the missed lessons after I recover from the illness.
Yours ever,.
尊敬的先生/女士;
今天我向您请一天假，因为我昨天晚上不小心感冒。
今天早上，我妈妈带我去看医生，医生告诉我要在床上呆几天。所以我很抱歉没有从学校，特别是你有趣的课。我从病中康复后，一定会弥补错过的课。
你永远的朋友，
7 July
Dear Mr. Smith,
On account of an attack of the flu with a severe headache, I shall be unable to attend classes today, for which I submit a certificate from the doctor. I shall be much obliged if I can get your permission.
Respectfully yours,
John Warner
Wang Li
尊敬的史密斯先生：
由于重感冒并伴随严重的头痛，我今天不能上课，特呈交医生证明。如获批准，不胜感激。
致
礼!
约翰·华纳
7月28日
Dear Sir,
I'm sorry to tell you that I can't go to school today, I've caught a cold because I swam in the school's swimming pool yesterday.
This morning I had a headache. After taking my temperature, my mother found that I had a high fever, immediately she took me to see a doctor, who advised me to stay in bed for 2 days. Now I am writing to you to ask for 2 days' sick leave.
With best wishes
Your student,
Tom
Dear Ms Yang,
I'm so sorry that I have got a cold.Because of the bad cold I can't go to school these days.As a result,I want to stay at home for days.Thank you.
ZangHua.
Dear Ms Yang,
I'm so sorry that I have got a cold.Because of the bad cold I can't go to school these days.As a result,I want to stay at home for days.Thank you.
ZangHua.
Dear Mr.,
I'm sorry to tell you that I caught a cold and I'm not feeling well now.I am adviced to stay in bed for two days and can't go to school then.But I think I'll get well soon and be back the day after tomorrow.
Yours sincerely,
Dear Mr/Ms ：
Today I'm writing to you to ask for a five-day leave, for I've got cold last night with carlessness.
This morning my mother took me to see the doctor,who told me to stay in bed for some days. So I am very sorry to be absent from school, especially your interesting lessons. I'll be sure to make up for the missed lessons after I recover from the illness.
Yours ever,
.
Dear Mr. Wang,
I am very sorry that I shall be unable to come to your classes today owing to a bad cold. I enclose a certificate from the doctor who is attending me. He said it will be two or three days before I shall be able to resume my school.
David
April 20
王老师：
很抱歉，我因患重感冒今天不能到校。现附上医生证明，他说我两三天后才能到校学习。
大卫
四月二十日