Hi Sandy.
-> Hi Sandy, 
To day have a poor voice.
-> Today, you have a poor / strange voice.
You have a sore throat.
-> Well done!
Sandy. Hope you get better soon.
-> Sandy, hope you get better soon.
Tomorrow lesson Telephone
-> Another telephone class for our next lesson tomorrow.
Have a good day.
->Have a good day!

Hi Peng!
A wonderful day!
Thanks for your concern. I really hope I'll get better to have quality classes with my students including you.
You are a good student so I do not worry about our class. I know you will still take part and study well.
About your message, I am happy because you did it on your own, so I understand it better. Keep it up!
Just take note of the correcions/revisions I made with your sentences.
It is a good practice that you use even very simple words to form a sentence. You'll get better soon.

-T. Sandy-