Dear Yoko,
I am terriblly sorry, I can not come to the class today.
Since I was absent from work for a couple of days last week I had lots of things to do and can not leave the office in ordinary time....
Thank you very much for the draft of the papar which you sent me the other day. I will send you back the draft tomorrow, and we can check the details.

Sarajean,
I will come to the class on 31st for presentation.
Sorry for my absence of today and last week.

Makiko