My father is fat.
My grandfather is old.
The boy is short.
This is my friend.

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Hello Andrew!

           I could always see that you are trying your best to express your ideas and you try to understand our lesson. Keep it up! :) Teacher is very happy that you can follow my instruction now. I will give out one example and you can do the rest of it. Just don't forget to be practice your grammar skill all the time and most especially what is being taught to you.  Your homework is one way to practice your grammar skill and I hope that you will always stay positive in learning the English language.

                  All of your sentence was correct. Maybe you just mistyped the letter in "This is my friend" :) Be careful with this. 

            Thank you for your time Andrew and take care of yourself.

T.Cassie ^_^